CN112638606A - Method for making non-oxide ceramic articles and for the manufacture of laminates of aerogel, xerogel and porous ceramic articles - Google Patents

Abstract

The present disclosure provides a method of making a non-oxide ceramic component. The method comprises obtaining a photopolymerizable slurry; selectively curing the photopolymerizable slurry to obtain a gelled article; drying the gelled article to form an aerogel or xerogel article; heat treating the aerogel or xerogel article to form a porous ceramic article; and sintering the porous ceramic article to obtain a sintered ceramic article. The photopolymerizable slurry comprises non-oxide ceramic particles; at least one radiation curable monomer; a solvent; a photoinitiator; an inhibitor; and at least one sintering aid. In addition, aerogels, xerogels, porous ceramic articles, and non-oxide ceramic articles are provided. Additionally, a method is provided that includes receiving, by a manufacturing device having one or more processors, a digital object containing data specifying an article of manufacture; and generating, with the manufacturing apparatus, an article of manufacture by a layup manufacturing process based on the digital object. A system is also provided, the system including a display that displays a 3D model of an article; and one or more processors responsive to the 3D model selected by the user to cause the 3D printer to produce a physical object of the artefact.

Description

Method for making non-oxide ceramic articles and for the manufacture of laminates of aerogel, xerogel and porous ceramic articles

Technical Field

The present disclosure broadly relates to a stack manufacturing method for producing ceramic articles using a slurry containing non-oxide particles as a build material. The invention also relates to articles obtainable by such a process.

Background

In conventional ceramic processing (e.g., slip casting), the ceramic slurry must generally have as high a particle loading as possible to obtain an intermediate with a high green density. High green densities are desired and required to enable the production of dense sintered ceramics.

Powder-based stack fabrication techniques (where a low bulk density of the powder bed produces a highly porous 3D object) typically do not produce high density ceramics without increasing a large amount of pressure during heat treatment, making it challenging to achieve dense complex three-dimensional shapes. Typically, this method results in a density of less than 95% of the theoretical density of the ceramic material.

Processing of slurries based on ceramic-filled photopolymer has shown promise due to their ability to be used as green bodies in the production of relatively dense ceramic articles having three-dimensional structures using stereolithography. At the same time, attempts have also been made to produce ceramic articles using stack-up manufacturing techniques (such as stereolithography), which are mainly used for processing polymers. For example, WO 2016/191162(Mayr et al) describes a stack manufacturing process using a sol containing nano-sized particles to produce ceramic articles.

Disclosure of Invention

In a first aspect, a method of making a non-oxide ceramic component is provided. The method comprises the following steps: a) obtaining a photopolymerizable slurry; b) selectively curing the photopolymerizable slurry to obtain a gelled article; c) drying the gelled article to form an aerogel or xerogel article; d) heat treating the aerogel or xerogel article to form a porous ceramic article; and e) sintering the porous ceramic article to obtain a sintered ceramic article. The photopolymerizable slurry comprises non-oxide ceramic particles; at least one radiation curable monomer; a solvent; a photoinitiator; an inhibitor; and at least one sintering aid.

In a second aspect, an aerogel is provided. The aerogel comprises: a) an organic material; b) non-oxide ceramic particles in a range from 29 to 75 weight percent based on the total weight percent of the aerogel; and c) at least one sintering aid.

In a third aspect, a xerogel is provided. The xerogel comprises: a) an organic material; b) non-oxide ceramic particles in a range of 29 to 75 weight percent based on the total weight percent of the xerogel; and c) at least one sintering aid.

In a fourth aspect, a porous ceramic article is provided. The porous ceramic article comprises: a) non-oxide ceramic particles in a range of 90 wt% to 99 wt%, based on the total weight of the porous ceramic article; and b) at least one sintering aid. The non-oxide ceramic particles define one or more tortuous or arcuate pathways, one or more internal architectural voids, one or more undercuts, one or more perforations, or a combination thereof in the porous ceramic article. The porous ceramic article includes at least one feature integral to the porous ceramic article, the feature having a dimension of 0.5mm in length or less.

In a fifth aspect, a non-oxide ceramic article is provided. The non-oxide ceramic material defines one or more tortuous or arcuate pathways, one or more internal architectural voids, one or more undercuts, one or more perforations, or a combination thereof in the non-oxide ceramic article. The non-oxide ceramic article exhibits a density of 95% or greater relative to a theoretical density of the non-oxide ceramic material. The non-oxide ceramic article includes at least one feature integral to the non-oxide ceramic article, the feature having a dimension of 0.5mm in length or less.

In a sixth aspect, another method is provided. The method comprises the following steps: a) retrieving data representing a 3D model of an article from a non-transitory machine-readable medium; b) executing, by one or more processors, a 3D printing application interfacing with a manufacturing device using the data; and c) creating a physical object of an article by the manufacturing apparatus, the article comprising a gelled article obtained by selectively curing the photopolymerizable slurry. The photopolymerizable slurry comprises non-oxide ceramic particles; at least one radiation curable monomer; a solvent; a photoinitiator; an inhibitor; and at least one sintering aid.

In a seventh aspect, another method is provided. The method comprises the following steps: a) receiving, by a manufacturing device having one or more processors, a digital object containing data specifying a plurality of layers of an article; and b) based on the digital object, generating an article by a laminate manufacturing process using a manufacturing apparatus, the article comprising a gelled article obtained by selectively curing the photopolymerizable slurry. The photopolymerizable slurry comprises non-oxide ceramic particles; at least one radiation curable monomer; a solvent; a photoinitiator; an inhibitor; and at least one sintering aid.

In an eighth aspect, a system is provided. The system includes a display that displays a 3D model of an article; and one or more processors responsive to the 3D model selected by the user to cause the 3D printer to produce a physical object of an article comprising a gelled article obtained by selectively curing the photopolymerizable slurry. The photopolymerizable slurry comprises non-oxide ceramic particles; at least one radiation curable monomer; a solvent; a photoinitiator; an inhibitor; and at least one sintering aid.

In a ninth aspect, a non-transitory machine readable medium is provided. The non-transitory machine readable medium contains data representing a three-dimensional model of an article that, when accessed by one or more processors interfaced with the 3D printer, causes the 3D printer to produce the article comprising a reaction product of the photopolymerizable slurry. The photopolymerizable slurry comprises non-oxide ceramic particles; at least one radiation curable monomer; a solvent; a photoinitiator; an inhibitor; and at least one sintering aid.

It has been found that ceramic parts made according to at least certain embodiments of the present disclosure exhibit acceptable densities despite low particle loading of the photopolymerizable composition.

The above summary of the present disclosure is not intended to describe each disclosed embodiment or every implementation of the present disclosure. The following description more particularly exemplifies illustrative embodiments. Guidance is provided throughout this application through lists of embodiments that can be used in various combinations. In each case, the lists cited are intended as representative groups only and are not to be construed as exclusive lists.

Drawings

FIG. 1 is a flow chart of a process for constructing an article using the photopolymerizable compositions disclosed herein.

Fig. 2 is a general schematic diagram of a three-dimensional photocuring molding device.

Fig. 3A is a perspective view of a gelled article made according to one embodiment of the present disclosure.

Figure 3B is a perspective view of an aerogel article formed from the gelled article of figure 3A,

FIG. 3C is a perspective view of a porous ceramic article formed from the aerogel article of FIG. 3B

Fig. 3D is a perspective view of a sintered ceramic article formed from the porous ceramic article of fig. 3C.

Fig. 4A is a perspective view of an aerogel article of comparative example 1.

Fig. 4B is a perspective view of a fragment of the sintered ceramic article of fig. 4A formed from the aerogel article of fig. 4A.

Fig. 5 is a general schematic of an apparatus in which radiation is directed through a container.

Fig. 6 is a block diagram of a general system 600 for stack-up manufacturing of an article.

FIG. 7 is a block diagram of a general manufacturing process for an article.

FIG. 8 is a high level flow chart of an exemplary article manufacturing process.

Fig. 9 is a high level flow chart of an exemplary article layup manufacturing process.

Fig. 10 is a schematic front view of an exemplary computing device 1000.

FIG. 11A is a perspective view of the gelled article of example 3.

FIG. 11B is a perspective view of a sintered article formed from the gelled article of FIG. 11A.

FIG. 12A is a perspective view of a gelled article of comparative example 5.

FIG. 12B is a perspective view of an aerogel article formed from the gelled article of FIG. 12A.

FIG. 13A is a perspective view of the gelled article of example 6.

FIG. 13B is a perspective view of an aerogel article formed from the gelled article of FIG. 13A.

Fig. 13C is a perspective view of a sintered ceramic article formed from the aerogel article of fig. 13B.

While the above-identified drawing figures set forth several embodiments of the disclosure, other embodiments are also contemplated, as noted in the specification. The figures are not necessarily to scale. In all cases, this disclosure presents the invention by way of representation and not limitation. It should be understood that numerous other modifications and embodiments can be devised by those skilled in the art, which fall within the scope and spirit of the principles of the invention.

Detailed Description

The present disclosure provides a method of producing a non-oxide ceramic component using laminate fabrication from a slurry of supported particles that would normally be highly light scattering and UV light curing the slurry using laminate fabrication techniques. Such techniques allow components with complex geometries and fine features that cannot be obtained using conventional non-oxide ceramic fabrication processes, such as hot pressing or machining, and should additionally reduce the tooling overhead for similarly sized components. Economical fabrication of non-oxide ceramic particles in nanoparticle size is often challenging, and therefore slurries with particles in the submicron to micron range are typically prepared. Such slurries are generally opaque to light due to the high degree of scattering from the particles. This means that such slurries are generally incompatible with the photocuring techniques required by most slurry-based stack fabrication techniques.

The low loading of non-oxide particles according to at least certain embodiments of the present disclosure enables lower composition viscosity and deeper cure depth during photopolymerization in a stack fabrication process (e.g., stereolithography), but unexpectedly, ceramic components can be produced after post-processing steps. For example, a round photomask having a diameter of 4mm was used and the light exposure on an Asiga Pico 23D printer (Asiga USA, Anaheim Hills, CA) was timed to analyze the depth of cure of a slurry containing non-oxide particles and to show a reasonable depth of cure at a cure time of less than ten seconds. However, at longer time scales, light scattering produces extensive overcuring as lighter areas around the curing circle. The relationship between cure depth and overcure is important; as the exposure required to obtain a suitable depth of cure from printing increases, the amount of over-cure increases. It is desirable to keep overcuring to a minimum to obtain a precisely printed part because overcuring causes parts to have flaking edges and can lead to print failures.

Glossary：

As used herein, "ceramic" or "ceramic article" means a non-metallic material produced by the application of heat. Ceramics are generally hard and brittle and, in contrast to glass or glass ceramics, exhibit a substantially fully crystalline structure. Ceramics are generally classified as inorganic materials. By "crystalline" is meant a solid composed of atoms arranged in a periodic pattern in three dimensions (i.e., having a long-range crystal structure, as can be determined by techniques such as X-ray diffraction). By "crystallite" is meant a crystalline domain of a solid having a defined crystalline structure. The crystallites may have only one crystalline phase.

As used herein, "laminate manufacturing" means a process for making a three-dimensional article. One example of a layup manufacturing technique is Stereolithography (SLA), in which successive layers of material are laid down under computer control. The article can have virtually any shape or geometry and be produced from a three-dimensional model or other source of electronic data.

As used herein, "slurry" refers to a continuous liquid phase comprising discrete particles having a size in the range of 1 nanometer (nm) to 50 micrometers or 1nm to 10 micrometers. Typically, most (i.e., more than 50%) of the particles have a diameter of 100nm or greater.

As used herein, "machining" refers to milling, grinding, cutting, engraving, or shaping a material by a machine. Milling is generally faster and less costly than grinding. A "machinable article" is an article that has a three-dimensional shape and sufficient strength to be machined.

As used herein, "powder" refers to a dry bulk material composed of a multitude of fine particles that are free flowing when shaken or tilted.

As used herein, "particle" refers to a substance that is a solid having a geometrically determinable shape. The shape may be regular or irregular. The particles can generally be analyzed with respect to, for example, particle size and particle size distribution. The particles may comprise one or more crystallites. Thus, the particles may comprise one or more crystalline phases.

As used herein, "association" refers to the aggregation of two or more primary particles that are aggregated and/or agglomerated. Similarly, the term "non-associated" refers to two or more primary particles that are not or substantially not aggregated and/or agglomerated.

As used herein, "aggregation" refers to a strong association of two or more primary particles. For example, the primary particles may be chemically bonded to each other. The breaking up of aggregates into smaller particles (e.g., primary particles) is often difficult to achieve.

As used herein, "agglomeration" refers to a weak association of two or more primary particles. For example, the particles may be held together by charge or polarity. The agglomerates are less difficult to break up into smaller particles (e.g., primary particles) than the aggregates.

As used herein, "primary particle size" refers to the size of non-associated single crystal non-oxide ceramic particles (which may be considered primary particles). The primary particle size is typically measured using X-ray diffraction (XRD).

As used herein, "soluble" means that the component (e.g., solid) can be completely dissolved within the solvent. That is, the material is capable of forming a discrete molecule (e.g., glucose), ion (e.g., sodium chloride), or non-settling particle (e.g., slurry) when dispersed in water at 23 ℃. However, the solubilization process may require some time, for example, it may require stirring the components within a few hours (e.g., 10 to 20 hours).

As used herein, "density" means the ratio of the mass to the volume of an object. The unit of density is usually grams per cubic centimeter (g/cm)³). The density of an object can be calculated, for example, by determining its volume (e.g., by calculation or applying archimedes' principle or method) and measuring its mass. Can be used as baseThe volume of the sample is determined from the overall external dimensions of the sample. The density of the sample can be calculated from the measured sample volume and the sample mass. The total volume of the material sample can be calculated from the mass of the sample and the density of the material used. The total volume of the pores in the sample was assumed to be the remainder of the sample volume (100% minus the total volume of the material).

As used herein, "theoretical density" refers to the maximum possible density that would be obtained in a sintered article if all of the pores were removed. The percentage of theoretical density of the sintered article can be determined, for example, from an electron micrograph of a cross section of the sintered article. The percentage of the area of the sintered article in the electron micrograph attributable to the pores can be calculated. In other words, the percentage of theoretical density can be calculated by subtracting the percentage of voids from 100%. That is, if the electron micrograph of the sintered product has 1% of the area attributed to the pores, the density of the sintered product is considered to be equal to 99% of the theoretical density. The density can also be determined by the archimedes method.

As used herein, in the ceramic art, "porous material" refers to a material that includes a partial volume formed by voids, pores, or pores. Accordingly, the "open-cell" structure of a material is sometimes referred to as an "open-cell" structure, and the "closed-cell" material structure is sometimes referred to as a "closed-cell" structure. It has also been found that the term "aperture" is sometimes used in the art in place of the term "small hole". The material structure classification "open" and "closed" can be determined for different porosities measured according to DIN 66133 for different material samples (e.g., using mercury "Poremaster 60-GT," available from Quantachrome inc., USA). Materials having an open cell or open porous structure may be traversed by, for example, a gas.

As used herein, "heat treatment" or "de-binding" refers to a process of heating a solid material to drive off at least 90% by weight of volatile chemically bound components (e.g., organic components) (as opposed to, for example, drying, where physically bound water is driven off by heating). The heat treatment is carried out at a temperature lower than the temperature required to carry out the sintering step.

As used herein, "sintering" and "firing" are used interchangeably. A porous (e.g., pre-sintered) ceramic article shrinks during the sintering step (i.e., if sufficient temperature is applied). The sintering temperature applied depends on the ceramic material selected. Sintering typically involves densifying a porous material into a less porous material having a higher density (or a material having less small pores), and in some cases sintering may also involve a change in the phase composition of the material (e.g., a partial transition of an amorphous phase to a crystalline phase).

As used herein, "green gel," "gelled article," and "gelled body" are used interchangeably and mean a three-dimensional gel resulting from the curing reaction of polymerizable components (including organic binders and solvents) contained in a slurry.

As used herein, "aerogel" means a three-dimensional low-density solid. Aerogels are porous materials derived from gels in which the liquid component of the gel is replaced with a gas. The removal of the solvent is usually carried out under supercritical conditions. During this process, the network does not substantially shrink and a highly porous, low density material can be obtained.

As used herein, "xerogel" refers to a three-dimensional solid derived from a green gel in which the liquid component of the gel has been removed by evaporation at ambient conditions or at elevated temperatures.

As used herein, "green body" means an unsintered ceramic article in which an organic binder is typically present.

As used herein, "green body" and "porous ceramic article" are interchangeable and refer to a pre-sintered ceramic article.

As used herein, "geometrically defined article" means an article whose shape can be described in geometric terms, including two-dimensional terms such as circular, square, rectangular, and three-dimensional terms such as layer, cube, cuboid, sphere.

As used herein, "isotropic linear sintering behavior" means that the sintering of the porous body that occurs during the sintering process is substantially invariant with respect to the directions x, y, and z. By "substantially constant" is meant that the difference in sintering behavior with respect to directions x, y and z is within a range of no more than about +/-5% or +/-2% or +/-1%.

As used herein, the term "cracking" refers to segregation or zoning (i.e., defects) of a material in a ratio equal to at least 5:1, at least 6:1, at least 7:1, at least 8:1, at least 10:1, at least 12:1, or at least 15:1 in any two dimensions.

Within the meaning of the present invention, a material or composition is "substantially free" or "substantially free of a component if it does not contain that component as an essential feature. Thus, the components are not arbitrarily added to the composition or material by themselves or in combination with other components or ingredients of other components. A composition or material that is substantially free of a component typically comprises the component in an amount of less than about 1 wt.%, or less than about 0.1 wt.%, or less than about 0.01 wt.% (or less than about 0.05mol/1 solvent or less than about 0.005mol/1 solvent or less than about 0.0005mol/1 solvent), relative to the composition or material as a whole. Ideally, the composition or material does not contain the components at all. However, it is sometimes unavoidable that a small amount of the component is present, for example, due to impurities.

As used herein, "aliphatic group" refers to a saturated or unsaturated, straight chain, branched chain, or cyclic hydrocarbon group. For example, the term is used to encompass alkyl groups, alkenyl groups, and alkynyl groups.

As used herein, "alkyl" refers to a straight or branched, cyclic or acyclic, saturated monovalent hydrocarbon group having one to thirty-two carbon atoms, such as methyl, ethyl, 1-propyl, 2-propyl, pentyl, and the like.

As used herein, "alkylene" means a straight chain saturated divalent hydrocarbon having one to twelve carbon atoms or a branched chain saturated divalent hydrocarbon having three to twelve carbon atoms, such as methylene, ethylene, propylene, 2-methylpropylene, pentylene, hexylene, and the like.

As used herein, "alkenyl" refers to a monovalent straight or branched chain unsaturated aliphatic group having one or more carbon-carbon double bonds, such as a vinyl group. Unless otherwise indicated, alkenyl groups typically contain one to twenty carbon atoms.

As used herein, the term "hardenable" refers to a material that can be cured or solidified, e.g., by heating to remove solvent, heating to cause polymerization, chemical crosslinking, radiation-induced polymerization or crosslinking, and the like.

As used herein, "curing" means hardening or partially hardening the composition by any mechanism, such as by heat, light, radiation, electron beam, microwave, chemical reaction, or combinations thereof.

As used herein, "cured" refers to a material or composition that has been hardened or partially hardened (e.g., polymerized or crosslinked) by curing.

As used herein, "integral" means made at the same time or cannot be separated without damaging one or more of the (integral) parts.

The term "(meth) acrylate" as used herein is a shorthand form for acrylate, methacrylate, or a combination thereof; "(meth) acrylic acid" is a shorthand for acrylic acid, methacrylic acid, or a combination thereof; "(meth) acryloyl" is a shorthand for acryloyl and methacryloyl. "acryloyl" refers to derivatives of acrylic acid such as acrylates, methacrylates, acrylamides, and methacrylamides. "(meth) acryl" refers to a monomer or oligomer having at least one acryl or methacryl group and, if two or more groups are included, linked by an aliphatic segment. As used herein, a "(meth) acrylate functional compound" is a compound that includes, among other things, a (meth) acrylate moiety.

As used herein, "non-crosslinkable" refers to a polymer that does not undergo crosslinking upon exposure to actinic radiation or elevated temperature. Typically, non-crosslinkable polymers are non-functional polymers such that they lack functional groups that will participate in crosslinking.

As used herein, "oligomer" refers to a molecule having one or more properties that change upon addition of a single additional repeat unit.

As used herein, "polymer" refers to a molecule having one or more properties that do not change upon addition of a single additional repeat unit.

As used herein, "polymerizable slurry" and "polymerizable composition" each mean a hardenable composition that can undergo polymerization upon initiation (e.g., free radical polymerization initiation). Typically, the polymerizable slurry or composition, prior to polymerization (e.g., hardening), has a viscosity profile that meets the requirements and parameters of one or more layup manufacturing (e.g., 3D printing) systems. For example, in some embodiments, in the case of a "photopolymerizable slurry," hardening includes irradiation with actinic radiation of sufficient energy to initiate polymerization or crosslinking reactions. For example, in some embodiments, Ultraviolet (UV) radiation, electron beam radiation, or both may be used.

As used herein, "resin" includes all polymerizable components (monomers, oligomers, and/or polymers) present in the hardenable slurry or composition. The resin may comprise only one polymerizable component compound or a mixture of different polymerizable compounds.

As used herein, "sintered article" refers to a gelled article that has been dried, heated to remove the organic matrix, and then further heated to reduce porosity and densify. The sintered density is at least 40% of theoretical density. Articles having a density in the range of 40% to 93% of theoretical density typically have an open porosity (pores open to the surface). Above 93% or 95% of theoretical density, there are typically closed cells (no pores open to the surface).

As used herein, "thermoplastic" refers to a polymer that flows when heated sufficiently above its glass transition point and becomes solid when cooled.

As used herein, "thermoset" refers to a polymer that permanently sets when cured and does not flow when subsequently heated. Thermosetting polymers are typically crosslinked polymers.

The words "preferred" and "preferably" refer to embodiments of the disclosure that may provide certain benefits under certain circumstances. However, other embodiments may also be preferred, under the same or other circumstances. Furthermore, the recitation of one or more preferred embodiments does not imply that other embodiments are not useful, and is not intended to exclude other embodiments from the scope of the disclosure.

In this application, terms such as "a," "an," and "the" are not intended to refer to only a single entity, but include the general class of which a specific example may be used for illustration. The terms "a", "an" and "the" are used interchangeably with the term "at least one". The phrases "at least one (kind) in … …" and "at least one (kind) comprising … …" in the following list refer to any one of the items in the list and any combination of two or more of the items in the list.

As used herein, the term "or" is generally employed in its ordinary sense, including "and/or" unless the context clearly dictates otherwise. The term "and/or" means one or all of the listed elements or a combination of any two or more of the listed elements.

Likewise, all numerical values herein are assumed to be modified by the term "about" and preferably by the term "exactly. As used herein, with respect to a measured quantity, the term "about" refers to a deviation in the measured quantity that is commensurate with the objective of the measurement and the accuracy of the measurement equipment used, as would be expected by a skilled artisan taking the measurement with some degree of care. Also herein, the recitations of numerical ranges by endpoints include all numbers subsumed within that range and the endpoints (e.g., 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, 5, etc.).

As used herein, as a modifier to a property or attribute, unless specifically defined otherwise, the term "substantially" means that the property or attribute will be readily identifiable by a person of ordinary skill without requiring an absolute precision or perfect match (e.g., within +/-20% for quantifiable properties). Unless specifically defined otherwise, the term "substantially" means a high degree of approximation (e.g., within +/-10% for quantifiable characteristics), but again does not require absolute precision or a perfect match. Terms such as identical, equal, uniform, constant, strict, etc., are to be understood as being within ordinary tolerances, or within measurement error applicable to the particular situation, rather than requiring an absolutely exact or perfect match.

In a first aspect, the present disclosure provides a method of making a non-oxide ceramic component. The method comprises the following steps:

a) obtaining a photopolymerizable slurry, the photopolymerizable slurry comprising non-oxide ceramic particles; at least one radiation curable monomer; a solvent; a photoinitiator; an inhibitor; and at least one sintering aid;

b) selectively curing the photopolymerizable slurry to obtain a gelled article;

c) drying the gelled article to form an aerogel or xerogel article;

d) heat treating the aerogel or xerogel article to form a porous ceramic article; and

e) sintering the porous ceramic article to obtain a sintered ceramic article.

In other words, and with reference to fig. 1, a method of making a non-oxide ceramic part includes a step 110 of obtaining a photopolymerizable slurry and a step 120 of selectively curing the photopolymerizable slurry to obtain a gelled article. In certain embodiments, selectively curing the photopolymerizable slurry comprises curing a portion of the photopolymerizable slurry having a thickness of 3 microns or greater, 4 microns or greater, 5 microns or greater, 7 microns or greater, 10 microns or greater, 15 microns or greater, 20 microns or greater, or 25 microns or greater; and has a thickness of 50 microns or less, 45 microns or less, 40 microns or less, 35 microns or less, or 30 microns or less; such as a thickness between 3 and 50 microns.

The photopolymerizable slurry is typically introduced into a reservoir, cartridge, or other suitable container for use by or in a stack-making apparatus. The stack fabrication apparatus selectively cures the photopolymerizable slurry in accordance with a set of computerized design instructions. Optionally, the method includes a step 130 of repeating step 120 to form a plurality (e.g., at least two, at least three, etc.) of layers of the gelled article.

Referring again to fig. 1, the method further includes a step 140a of drying the gelled article to form an aerogel article or a step 140b of drying the gelled article to form a xerogel article. Optionally, drying is performed by applying a supercritical fluid drying step.

The method further includes the step 150a of heat treating the aerogel article to form a porous ceramic article or the step 150b of heat treating the xerogel article to form a porous ceramic article; and a step 160 of sintering the porous ceramic article to obtain a sintered ceramic article. In certain embodiments, the sintered ceramic article includes at least one feature integral to the sintered ceramic article having a dimension of 0.5mm in length or less. The photopolymerizable slurry comprises non-oxide ceramic particles; at least one radiation curable monomer; a solvent; a photoinitiator; an inhibitor; and at least one sintering aid.

Additionally, it should be understood that the methods of manufacturing 3D articles described herein may include so-called "stereolithography/compatibilization polymerization" 3D printing methods, and that the selective curing step may be printed using stereolithography. Other techniques for three-dimensional fabrication are known and may be suitably adapted for use in the applications described herein. More generally, three-dimensional fabrication techniques become available. All such techniques are suitable for use with the photopolymerizable slurries described herein, provided that they provide compatible manufacturing viscosities and resolution for the specified article characteristics. Data representing the three-dimensional object may be used for manufacturing using any of the manufacturing techniques described herein (alone or in various combinations), which may be reformatted or otherwise adapted as desired for a particular printing or other manufacturing technique.

It is entirely possible to form 3D articles from the photopolymerizable slurries described herein using compatibilization polymerization (e.g., stereolithography). For example, in some cases, a method of printing a 3D article includes retaining a photopolymerizable slurry described herein in a fluid state in a container, and selectively applying energy to the photopolymerizable composition in the container to solidify at least a portion of the fluid layer of the photopolymerizable composition, thereby forming a hardened layer that defines a cross-section of the 3D article. Additionally, the methods described herein may further include raising or lowering the hardened layer of photopolymerizable slurry (e.g., green body) to provide a new or second fluid layer of unhardened photopolymerizable slurry at the surface of the fluid in the container, and then again selectively applying energy to the photopolymerizable slurry in the container to solidify at least a portion of the new or second fluid layer of photopolymerizable slurry to form a second solidified layer defining a second cross-section of the 3D article. In addition, the first and second cross-sections of the 3D article can be bonded or adhered to each other in the z-direction (or build direction corresponding to the above-described raised or lowered direction) by applying energy for setting the photopolymerizable slurry. Further, selectively applying energy to the photopolymerizable slurry in the container may comprise applying actinic radiation, such as UV radiation, visible radiation, or electron beam radiation, of sufficient energy to cure the photopolymerizable slurry. The methods described herein may also include planarizing the new layer of fluid photopolymerizable slurry provided by raising or lowering the elevator platform. Such planarization may be performed in some cases by utilizing a wiper or roller or recoater. Planarization corrects for the thickness of one or more layers prior to curing by flattening the dispensed material to remove excess material and form a uniform smooth exposed or flat upwardly facing surface on the support platform of the printer.

It should also be appreciated that the foregoing process may be repeated a selected number of times to provide a 3D article. For example, in some cases, this process may be repeated "n" times. Additionally, it should be understood that one or more steps in the methods described herein, such as the step of selectively applying energy to the photopolymerizable slurry layer, may be performed according to an image of the 3D article in a computer-readable format. Suitable stereolithography printers include Viper Pro SLA from 3D Systems of rockhill, south carolina (3D Systems, Rock Hill, SC), and Asiga picoplus 39 from Asiga USA of arnish Hill, california (Asiga USA, Anaheim Hills, CA).

Fig. 2 illustrates an exemplary stereolithography apparatus ("SLA") that may be used with the photopolymerizable slurries and methods described herein. In general, SLA 200 may include a laser 202, optics 204, a turning lens 206, a lift 208, a platform 210, and a straight edge 212 within a cylinder 214 filled with a photopolymerizable slurry. In operation, the laser 202 is directed across the surface of the photopolymerizable slurry to cure a cross-section of the photopolymerizable slurry, after which the elevator 208 lowers the platform 210 slightly and another cross-section is cured. Straight edges 212 may scan the surface of the cured composition between layers to smooth and normalize the surface before adding new layers. In other embodiments, the vat 214 can be slowly filled with liquid resin as the article is stretched layer-by-layer onto the top surface of the photopolymerizable syrup.

The related art, namely compatibilization polymerization involving digital light processing ("DLP"), also employs containers of curable polymers (e.g., photopolymerizable syrup). However, in DLP-based systems, a two-dimensional cross-section is projected onto a curable material to cure a desired portion transverse to the entire plane of the projected beam at one time. All such curable polymer systems that may be suitable for use with the photopolymerizable slurries described herein are intended to fall within the scope of the terms "compatibilization polymerization" and "stereolithography" as used herein. In certain embodiments, devices suitable for use in continuous mode may be employed, such as those commercially available from Carbon 3D corporation (Carbon 3D, Inc. (Redwood City, CA)) of Redwood City, california, for example, as described in U.S. patents 9,205,601 and 9,360,757 (both to DeSimone et al).

Referring to fig. 5, a general schematic of another SLA facility that may be used with the photopolymerizable slurries and processes described herein is provided. In general, the apparatus 500 may include a laser 502, optics 504, a turning lens 506, a lift 508, and a platform 510 within a cylinder 514 filled with a photopolymerizable slurry 519. In operation, the laser 502 is directed through a wall 520 (e.g., floor) of the cylinder 514 and into the photopolymerizable slurry to cure a cross-section of the photopolymerizable slurry 519 to form the article 517, after which the lift 508 slightly raises the platform 510 and another cross-section is cured. Thus, the radiation may be directed through a wall, such as a side wall or a bottom wall, of a container (e.g., a tank) containing the photopolymerizable slurry.

More generally, photopolymerizable slurries are typically cured using actinic radiation (such as UV radiation, electron beam radiation, visible radiation, or any combination thereof). One skilled in the art can select the appropriate radiation source and wavelength range for a particular application without undue experimentation.

After the 3D article is formed, it is typically removed from the laminate manufacturing equipment and rinsed (e.g., ultrasonic or bubbling or spraying in a solvent), which will dissolve a portion of the uncured photopolymerizable slurry, but not the cured solid article (e.g., green body). Any other conventional method for cleaning an article and removing uncured material from the surface of the article may also be utilized. At this stage, the three-dimensional article typically has sufficient green strength for processing in the remaining (e.g., optional) steps of the method.

In some embodiments, a photopolymerizable slurry described herein in a cured state may exhibit one or more desired properties. A photopolymerizable slurry in a "cured" state may include a photopolymerizable slurry that includes polymerizable components that have been at least partially polymerized and/or crosslinked. For example, in some cases, the gelled article is at least about 10% polymerized or crosslinked, or at least about 30% polymerized or crosslinked. In some cases, the gelled article is at least about 50%, at least about 70%, at least about 80%, or at least about 90% polymerized or crosslinked. The gelled article may also be polymerized or crosslinked between about 10% and about 99%.

The surface of the article, as well as the bulk article itself, typically still retains uncured photopolymerizable material, indicating further curing. Removal of residual uncured photopolymerizable composition is particularly useful when the article is to be subsequently post-cured to minimize the undesirable direct curing of the uncured residual photopolymerizable composition onto the article.

Further curing may be achieved by further irradiation with actinic radiation, heating, or both, plus optionally soaking the gelled article with another solvent (e.g., diethylene glycol ethyl ether or ethanol). Exposure to actinic radiation can be accomplished with any convenient source of radiation, typically UV radiation, visible radiation, and/or electron beam radiation, for a time in the range of about 10 to over 60 minutes. Heating is typically carried out at a temperature in the range of about 35 ℃ to 80 ℃ in an inert atmosphere for a time in the range of about 10 minutes to over 60 minutes. So-called post-cure ovens that combine UV radiation and thermal energy are particularly suitable for use in one or more post-cure processes. Generally, post-curing improves the mechanical properties and stability of the three-dimensional article relative to the same three-dimensional article without post-curing.

The components of the photopolymerizable slurry (e.g., the non-oxide ceramic particles, the radiation curable monomer, the photoinitiator, the inhibitor, and the sintering aid) are each discussed in detail below.

Non-oxide ceramic particles

The photopolymerizable compositions of the disclosure comprise particles of at least one non-oxide ceramic material.

Preferably, the non-oxide ceramic particles are selected from silicon carbide, silicon nitride (Si)₃N₄) Boron carbide (B)₄C) Titanium diboride (TiB)₂) Zirconium diboride (ZrB)₂) Boron Nitride (BN), titanium carbide (TiC), zirconium carbide (ZrC), aluminum nitride (AlN), calcium hexaboride (CaB)₆) MAX phase (M)_n+1AX_n) And any combination thereof. In a selected embodiment, a high-purity powder is used, wherein the total content of metal impurities is preferably less than 100ppm, particularly preferably less than 50 ppm. In an alternative embodiment, a powder having a total content of metal impurities of about 2,000ppm is used.

Suitable silicon nitride particles include, for example, but are not limited to, particles having an average particle size or average agglomerate particle size (D) of 0.5 microns to 20 microns, such as 1 micron to 10 microns₅₀) The powder of (4). The silicon nitride powder preferably has an oxygen content of less than 2 wt.% and a total carbon content of less than 0.35 wt.%. Commercially available silicon nitride powders are available from trasber, germany under the trade designation SILZOTThe Kencon Group (Alzchem Group AG, Trastber, Germany).

Suitable boron carbide particles include, for example and without limitation, those having a purity of 97 wt.% or greater and an average particle size (D) of 0.1 to 8 microns₅₀) B of (A)₄And C, powder. An example of a suitable boron carbide powder is 3M boron carbide powder commercially available from 3M Company (3M Company, st. paul, MN), st.

Suitable titanium diboride particles include, for example and without limitation, titanium diboride particles having an average particle size (D) of about 2 microns to 20 microns₅₀) Of TiB₂And (3) powder. An example of a suitable titanium diboride powder is 3M titanium diboride powder commercially available from 3M Company (3M Company).

Suitable zirconium diboride particles include, for example and without limitation, high purity or ultra-high purity ZrB available from American Elements, Los Angeles, CA₂And (3) powder.

Suitable boron nitride particles include, for example and without limitation, agglomerates of platelet-shaped hexagonal boron nitride primary particles, wherein the hexagonal boron nitride primary particles are connected to each other using an inorganic binding phase. The inorganic binder phase comprises at least one nitride and/or oxynitride. The nitride or oxynitride is preferably a compound of the elements aluminum, silicon, titanium and boron. An example of a suitable Boron Nitride powder is 3M Boron Nitride Cooling filler Platelets (3M Boron Nitride Cooling Fillers plates) commercially available from 3M Company (3M Company).

Suitable titanium carbide particles include, for example, those having an average particle size (D) of 1 to 3 microns₅₀) The TiC powder of (1). An example of a suitable titanium carbide powder is high vacuum grade 120 TiC commercially available from Hellman Starck, Munich, Germany.

Suitable zirconium carbide particles include, for example, particles having an average particle size (D) of 3 to 5 microns₅₀) ZrC powder of (4). An example of a suitable zirconium carbide powder is class B ZrC, commercially available from helmann Starck (HC-Starck).

Suitable aluminum nitride particles include, for example, particles having an average particle size (D) of 0.8 to 2 microns₅₀) The AlN powder of (1). An example of a suitable aluminum nitride powder is class C AlN, commercially available from hellman Starck corporation (HC-Starck).

Suitable calcium hexaboride particles include, for example, CaB commercially available from 3M Company (3M Company) under the trade designation 3M calcium hexaboride₆And (3) powder.

MAX phase particles are of the formula M_n+1AX_nWherein n ═ 1 to 3, M is an early transition metal, a is a group a element, and X is independently selected from carbon and nitrogen. The group a element is preferably an element 13 to 16. An example of a suitable MAX phase powder is MAXTHAL 312 powder, which is commercially available from kannel corporation of halstahama, Sweden, swenshi.

In some embodiments, the photopolymerizable slurry comprises 20 wt% or more of the non-oxide ceramic particles based on the total weight of the photopolymerizable slurry, the photopolymerizable slurry comprising 21 wt% or more, 22 wt% or more, 23 wt% or more, 24 wt% or more, 25 wt% or more, 26 wt% or more, 27 wt% or more, or 28 wt% or more based on the total weight of the photopolymerizable slurry; and less than 30 wt%, 29.5 wt% or less, 28.5 wt% or less, 27.5 wt% or less, 26.5 wt% or less, 25.5 wt% or less, or 24.5 wt% or less of non-oxide ceramic particles. In other words, the photopolymerizable slurry may comprise between 20 wt% and up to 30 wt% of the non-oxide ceramic particles, but not including 30 wt%, based on the total weight of the photopolymerizable slurry.

The non-oxide ceramic particles typically comprise an average (mean) particle size (i.e., D) of 250 nanometers (nm) or greater, 350nm or greater, 500nm or greater, 750nm or greater, 1 micron or greater, 1.25 microns or greater, 1.5 microns or greater, 1.75 microns or greater, 2 microns or greater, 2.5 microns or greater, 3.0 microns or greater, 3.5 microns or greater, 4.0 microns or greater, or 4.5 microns or greater₅₀) (ii) a And 10 microns or less, 9.5 microns or less, 9 microns or less, 8.5 microns or less, 8 micronsOr less, 7.5 microns or less, 7 microns or less, 6.5 microns or less, 6 microns or less, 5.5 microns or less, 5 microns or less, 4.5 microns or less, 3 microns or less, 2 microns or less, 1.5 microns or less, or 1 micron or less D₅₀. In other words, the non-oxide ceramic particles can have an average particle size (D) of 1 micron to 10 microns, 500 nanometers to 1.5 microns, or 250nm to 1 micron₅₀). Average (mean) particle size (D)₅₀) Refers to a particle size at which 50 volume percent of the particles in the particle distribution have a diameter of that diameter or less, as measured by laser diffraction. Preferably, the average particle size is the size of the primary particles.

Sintering aid

The photopolymerizable compositions of the disclosure comprise at least one sintering aid. Generally, the sintering aid aids aid in the removal of oxygen during the sintering process. In addition, the sintering aid may provide a phase that melts from a solid to a liquid at a lower temperature than the non-oxide ceramic material, or may provide some alternative mechanism to improve the transport of ceramic ions and thus increase densification compared to compositions that do not include the sintering aid.

Suitable sintering aids are not particularly limited and may include rare earth oxides, alkaline earth oxides, alkali oxides, and combinations thereof. Materials that produce a liquid at the sintering temperature of the non-oxide ceramic particles may be useful.

The rare earth oxide includes cerium oxide (e.g., CeO)₂) Dysprosium oxide (e.g., Dy)₂O₃) Erbium oxide (e.g., Er)₂O₃) Europium oxide (e.g., Eu)₂O₃) Gadolinium oxide (e.g., Gd)₂O₃) Holmium oxide (e.g., Ho)₂O₃) Lanthanum oxide (e.g., La)₂O₃) Lanthanum aluminum oxide (La AlO)₃) Lutetium oxide (e.g., Lu)₂O₃) Neodymium oxide (e.g., Nd)₂O₃) Praseodymium oxide (e.g., Pr)₆O₁₁) Samarium oxide (e.g., Sm)₂O₃) Terbium oxide(e.g., Tb)₂O₃) Thorium oxide (e.g., Th)₄O₇) Thulium oxide (e.g., Tm)₂O₃) And ytterbium oxide (e.g., Yb)₂O₃) And combinations thereof.

Alkaline earth metal oxides include barium oxide (BaO), calcium oxide (CaO), strontium oxide (SrO), magnesium oxide (MgO), beryllium oxide (BeO), and combinations thereof.

The alkali metal oxide includes lithium oxide (Li)₂O₂) Sodium oxide (Na)₂O₂) Potassium oxide (K)₂O), rubidium oxide (Rb)₂O) and cesium oxide (Cs)₂O) and combinations thereof.

In some embodiments, mixtures of alkaline earth metal oxides and rare earth oxides are preferred, such as compositions of alumina and yttria.

Additional suitable sintering aids include, for example, but are not limited to, boron, carbon, magnesium, aluminum, silicon, titanium, vanadium, chromium, iron, nickel, copper, aluminum nitride, alumina, ethyl silicate, sodium silicate, and Mg (NO)₃)₂Other glass, Fe₂O₃、MgF₂And combinations thereof.

In many embodiments, the at least one sintering aid comprises alumina, yttria, zirconia, silica, titania, magnesia, calcia, strontium oxide, baria, lithia, sodium oxide, potassia, carbon, boron carbide, aluminum nitride, or combinations thereof. For example, suitable commercially available sintering aids include calcined alumina from Ammi corporation (Almatis, Ludwigshafen, Germany) of Lodvieh, Germany and yttria from Treibacher Industrie AG, Althofen, Austria of Trilibach, Austria.

Radiation curable monomer

The photopolymerizable slurries described herein comprise one or more radiation curable monomers that are part of or form the organic matrix.

The one or more radiation curable monomers present in the photopolymerizable slurry may be described as a first monomer, a second monomer, a third monomer, and the like. The nature and structure of the radiation-curable monomer or monomers are not particularly limited unless the desired result cannot be achieved. In some embodiments, the at least one radiation curable monomer comprises an acrylate.

Upon polymerization, the radiation curable monomer forms a network with (preferably) uniformly dispersed non-oxide ceramic particles.

According to one embodiment, the photopolymerizable slurry comprises a polymerizable surface modifier as the first monomer. Optionally, at least a portion of the non-oxide ceramic particles in the photopolymerizable slurry may comprise a surface modifier attached to the surface of the non-oxide ceramic particles. The surface modifying agent may help to improve the compatibility of the particles contained in the slurry with the organic matrix material also present in the slurry. The surface modifying agent can be represented by the formula a-B, wherein the a group is capable of attaching to the surface of the non-oxide ceramic particle and the B group is radiation curable.

The group a may be attached to the surface of the non-oxide ceramic particle by adsorption, formation of ionic bonds, formation of covalent bonds, or a combination thereof. Examples of suitable moieties of group a include acidic moieties (such as carboxylic acid groups, phosphoric acid groups, sulfonic acid groups, and anions thereof) and silanes. The group B comprises a radiation curable moiety. Examples of suitable moieties of the group B include vinyl, in particular acryloyl or methacryloyl moieties.

Suitable surface modifying agents include polymerizable carboxylic acids and/or anions thereof, polymerizable sulfonic acids and/or anions thereof, polymerizable phosphoric acids and/or anions thereof, and polymerizable silanes. Suitable surface-modifying agents are also described, for example, in WO 2009/085926(Kolb et al), the disclosure of which is incorporated herein by reference.

Examples of free radically polymerizable surface modifying agents are polymerizable surface modifying agents comprising acidic moieties or anions thereof (e.g., carboxylic acid groups). Exemplary acidic free-radically polymerizable surface-modifying agents include acrylic acid, methacrylic acid, β -carboxyethyl acrylate, and mono-2- (methacryloyloxyethyl) succinate.

Exemplary free radically polymerizable surface-modifying agents can be the reaction product of a hydroxyl-containing polymerizable monomer and a cyclic anhydride such as succinic, maleic, and phthalic anhydride. Exemplary polymeric hydroxyl-containing monomers include hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, hydroxybutyl acrylate, and hydroxybutyl methacrylate. Acryloxy and methacryloxy functional polyethylene oxides and polypropylene oxides are also useful as polymerizable hydroxyl-containing monomers.

An exemplary free radically polymerizable surface modifier that imparts both polar character and reactivity to the non-oxide ceramic nanoparticles is mono (methacryloyloxypolyethylene glycol) succinate.

Another example of a free radically polymerizable surface modifying agent is a polymerizable silane. Exemplary polymerizable silanes include methacryloxyalkyltrialkoxysilanes or acryloxy-alkyltrialkoxysilanes (e.g., 3-methacryloxy-oxypropyltrimethoxysilane, 3-acryloxypropyl-trimethoxysilane, and 3- (methacryloxy) propyltriethoxysilane; e.g., 3- (methacryloxy) -propylmethyl-dimethoxy-silane and 3- (acryloxypropyl) methyldimethoxysilane); methacryloxyalkyl-dialkyl-alkoxy-silanes or acryloxyalkyl dialkyl alkoxy-silanes (e.g., 3- (methacryloyloxy) -propyldimethylethoxysilane); mercapto-alkyl-trialkoxysilanes (e.g., 3-mercapto-propyltrimethoxysilane); aryl trialkoxysilanes (e.g., styryl ethyl trimethoxysilane); vinyl silanes (e.g., vinylmethyldiacetoxysilane, vinyldimethyl-ethoxy-silane, vinylmethyldiethoxysilane, vinyltrimethoxy-silane, vinyltriethoxysilane, vinyltriacetoxysilane, vinyltriisopropoxysilane, vinyltrimethoxysilane, and vinyltris (2-methoxyethoxy) silane).

The surface modifying agent can be added to the non-oxide ceramic particles using conventional techniques. The surface modifying agent may be added before or after any removal of at least a portion of the carboxylic acid and/or anion thereof from the non-oxide ceramic particle-based slurry. The surface modifier may be added before or after the water is removed from the non-oxide ceramic particle-based slurry. The organic matrix may be added before or after the surface modification or simultaneously with the surface modification. Various methods of adding surface modifiers are also described, for example, in WO 2009/085926(Kolb et al), the disclosure of which is incorporated herein by reference.

The surface modification reaction may be carried out at room temperature (e.g., 20 ℃ to 25 ℃) or at elevated temperature (e.g., up to 95 ℃). When the surface modifying agent is an acid, such as a carboxylic acid, the non-oxide ceramic particles can be surface modified, typically at room temperature. When the surface modifying agent is a silane, the non-oxide ceramic particles are typically surface modified at elevated temperatures.

The first monomer may serve as a polymerizable surface modifier. A plurality of first monomers may be used. The first monomer may be the only surface modifier or may be combined with one or more other non-polymerizable surface modifiers. In some embodiments, the amount of the first monomer is at least 20 weight percent based on the total weight of the polymerizable material. For example, the amount of the first monomer is typically at least 25 wt.%, at least 30 wt.%, at least 35 wt.%, or at least 40 wt.%. The amount of the first monomer may be up to 100 wt%, up to 90 wt%, up to 80 wt%, up to 70 wt%, up to 60 wt%, or up to 50 wt%. Some photopolymerizable slurries include 20 to 100, 20 to 80, 20 to 60, 20 to 50, or 30 to 50 weight percent of the first monomer, based on the total weight of the polymerizable material.

The first monomer (i.e., polymerizable surface modifying agent) can be the only monomer in the polymerizable material, or it can be combined with one or more second monomers, as described in further detail below.

According to one embodiment, the photopolymerizable slurry comprises one or more second monomers comprising at least one or two radiation curable moieties. In particular, the second monomer comprising at least two radiation curable moieties may act as one or more crosslinkers during the gel forming step. Any suitable second monomer that does not have a surface modifying group can be used. The second monomer has no group capable of attaching to the surface of the non-oxide ceramic particle.

Successful construction typically requires a certain level of green gel strength and shape resolution. The crosslinking process generally allows greater green gel strength to be achieved at lower energy doses because the polymerization results in a stronger network. In some examples, higher energy doses have been applied to increase the layer adhesion of non-crosslinked systems. While the article is successfully built, the higher energy often affects the resolution of the final article, resulting in potentially multiple degrees of building, especially in the case of highly translucent materials where light and the depth of cure therewith can penetrate further into the material. The presence of a monomer having multiple polymerizable groups tends to enhance the strength of the gel composition formed upon polymerization of the photopolymerizable slurry. Such gel compositions can be more easily processed without cracking. The amount of monomer having multiple polymerizable groups can be used to adjust the flexibility and strength of the green body gel and indirectly optimize the green body gel resolution and the final article resolution.

In the case of applying a light source from below, it has been found that applying, for example, a cross-linking chemistry can help increase the adhesion strength between the layers, such that when the build platform is raised after the curing step, the newly cured layer moves with the build shape, rather than separating from the rest of the build and remaining on the transparent film, which would be considered an unacceptable build. Successful build can be defined as a scenario where the material adheres better to previously cured layers than the build pallet film to allow the three-dimensional structure to grow one layer at a time. Theoretically, this property can be achieved by applying an increased energy dose (higher power or longer light exposure) to provide stronger adhesion up to a certain point characteristic of the bulk material. However, in a fairly transparent system in the absence of light absorbing additives, higher energy exposure will eventually provide a cure depth significantly greater than the "sheet thickness", resulting in an overcure condition where the resolution of the part significantly exceeds the resolution of the "sheet thickness".

The addition of a radiation curable component comprising at least two radiation curable moieties to the photopolymerizable slurries described herein may facilitate the optimization of resolution as well as green strength. In the case of converting the green body into a fully dense ceramic, the increased gel strength of the green body contributes to the robustness of the post-construction procedure.

That is, the optional second monomer does not have a carboxylic acid group or a silyl group. The second monomer is typically a polar monomer (e.g., a non-acidic polar monomer), a monomer having multiple polymerizable groups, an alkyl (meth) acrylate, and mixtures thereof.

The overall composition of the polymerizable material is typically selected such that the polymerized material is soluble in the solvent medium. Homogeneity of the organic phase is generally preferred to avoid phase separation of the organic components in the gel composition. This tends to result in the formation of smaller and more uniform pores (pores with a narrow size distribution) in the subsequently formed aerogel or xerogel. In addition, the overall composition of the polymerizable material can be selected to adjust compatibility with the solvent medium and to adjust the strength, flexibility, and uniformity of the gel composition. In addition, the overall composition of the polymerizable material can be selected to adjust the burn-out characteristics of the organic material prior to sintering.

In many embodiments, the second monomer comprises a monomer having a plurality of polymerizable groups. The amount of polymerizable groups may be in the range of 2 to 6 or even higher. In many embodiments, the amount of polymerizable groups ranges from 2 to 5 or from 2 to 4. The polymerizable group is typically a (meth) acryloyl group.

Exemplary monomers having two (meth) acryloyl groups include 1, 2-ethanediol diacrylate, 1, 3-propanediol diacrylate, 1, 9-nonanediol diacrylate, 1, 12-dodecanediol diacrylate, 1, 4-butanediol diacrylate, 1, 6-hexanediol diacrylate, butanediol diacrylate, bisphenol A diacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, tetraethylene glycol diacrylate, tripropylene glycol diacrylate, polyethylene glycol diacrylate, polypropylene glycol diacrylate, polyethylene/polypropylene copolymer diacrylate, polybutadiene di (meth) acrylate, propoxylated glycerol tri (meth) acrylate, and neopentyl glycol hydroxypivalate diacrylate modified caprolactone.

Exemplary monomers having three or four (meth) acryloyl groups include, but are not limited to, trimethylolpropane triacrylate (e.g., commercially available from Cytec Industries, Inc. (Smyrna, GA, USA), under the trade designation TMPTA-N, and SR-351, commercially available from Sartomer, Exxon, Pa.), pentaerythritol triacrylate (e.g., commercially available from Sartomer, Pa.), ethoxylated (3) trimethylolpropane triacrylate (e.g., commercially available from Sartomer, under the trade designation SR-454), ethoxylated (4) pentaerythritol tetraacrylate (e.g., commercially available from Sartomer, etc.), ethoxylated (3) trimethylolpropane triacrylate (e.g., commercially available from Sartomer, under the trade designation SR-494), Tris (2-hydroxyethylisocyanurate) triacrylate (e.g., commercially available from Sartomer under the trade designation SR-368), a mixture of pentaerythritol triacrylate and pentaerythritol tetraacrylate (e.g., commercially available from cyanogen Industries, Inc., under the trade designation PETIA (where the ratio of tetraacrylate to triacrylate is about 1:1) and PETA-K (where the ratio of tetraacrylate to triacrylate is about 3: 1)), pentaerythritol tetraacrylate (e.g., commercially available from Sartomer under the trade designation SR-295), and ditrimethylolpropane tetraacrylate (e.g., commercially available from Sartomer under the trade designation SR-355).

Exemplary monomers having five or six (meth) acryloyl groups include, but are not limited to, dipentaerythritol pentaacrylate (e.g., commercially available from Sartomer under the trade designation SR-399) and hexafunctional urethane acrylates (e.g., commercially available from Sartomer under the trade designation CN 975).

Some photopolymerizable compositions comprise 0 to 80 weight percent of a second monomer having a plurality of polymerizable groups, based on the total weight of the polymerizable material. For example, the amount can range from 10 wt% to 80 wt%, 20 wt% to 80 wt%, 30 wt% to 80 wt%, 40 wt% to 80 wt%, 10 wt% to 70 wt%, 10 wt% to 50 wt%, 10 wt% to 40 wt%, or 10 wt% to 30 wt%.

In some embodiments, the optional second monomer is a polar monomer. As used herein, the term "polar monomer" refers to a monomer having a free radical polymerizable group and a polar group. The polar groups are typically non-acidic and typically comprise a hydroxyl group, a primary amido group, a secondary amido group, a tertiary amido group, an amino group, or an ether group (i.e., a group comprising at least one alkylene-oxy-alkylene group of the formula-R-O-R-, wherein each R is an alkylene group having from 1 to 4 carbon atoms).

Suitable optional polar monomers having hydroxyl groups include, but are not limited to, hydroxyalkyl (meth) acrylates (e.g., 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, and 4-hydroxybutyl (meth) acrylate), and hydroxyalkyl (meth) acrylamides (e.g., 2-hydroxyethyl (meth) acrylamide or 3-hydroxypropyl (meth) acrylamide), ethoxylated hydroxyethyl (meth) acrylate (e.g., monomers commercially available from Sartomer under the trade names CD570, CD571, and CD 572), and aryloxy substituted hydroxyalkyl (meth) acrylates (e.g., 2-hydroxy-2-phenoxypropyl (meth) acrylate).

Exemplary polar monomers containing primary amido groups include (meth) acrylamide. Exemplary polar monomers containing secondary amido groups include, but are not limited to: n-alkyl (meth) acrylamides such as N-methyl (meth) acrylamide, N-ethyl (meth) acrylamide, N-isopropyl (meth) acrylamide, N-t-octyl (meth) acrylamide, and N-octyl (meth) acrylamide. Exemplary polar monomers containing tertiary amide groups include, but are not limited to: n-vinylcaprolactam, N-vinyl-2-pyrrolidone, (meth) acryloylmorpholine and N, N-dialkyl (meth) acrylamides such as N, N-dimethyl (meth) acrylamide, N-diethyl (meth) acrylamide, N-dipropyl (meth) acrylamide and N, N-dibutyl (meth) acrylamide.

Polar monomers having amino groups include various N, N-dialkylaminoalkyl (meth) acrylates and N, N-dialkylaminoalkyl (meth) acrylamides. Examples include, but are not limited to: n, N-dimethylaminoethyl (meth) acrylate, N-dimethylaminoethyl (meth) acrylamide, N-dimethylaminopropyl (meth) acrylate, N-dimethylaminopropyl (meth) acrylamide, N-diethylaminoethyl (meth) acrylate, N-diethylaminoethyl (meth) acrylamide, N-diethylaminopropyl (meth) acrylate, and N, N-diethylaminopropyl (meth) acrylamide.

Exemplary polar monomers having ether groups include, but are not limited to, alkoxylated alkyl (meth) acrylates such as carbitol (meth) acrylate, 2-methoxyethyl (meth) acrylate, and 2-ethoxyethyl (meth) acrylate; and poly (alkylene oxide) (meth) acrylates such as poly (ethylene oxide) (meth) acrylate and poly (propylene oxide) (meth) acrylate. Poly (alkylene oxide) acrylates are often referred to as poly (alkylene glycol) (meth) acrylates. These monomers may have any suitable end groups, such as hydroxyl groups or alkoxy groups. For example, when the end group is a methoxy group, the monomer may be referred to as methoxy poly (ethylene glycol) (meth) acrylate.

Suitable alkyl (meth) acrylates that can be used as the second monomer can have an alkyl group that contains a linear, branched, or cyclic structure. Examples of suitable alkyl (meth) acrylates include, but are not limited to, methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, n-pentyl (meth) acrylate, 2-methylbutyl (meth) acrylate, n-hexyl (meth) acrylate, cyclohexyl (meth) acrylate, 4-methyl-2-pentyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, 2-methylhexyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, 2-octyl (meth) acrylate, isononyl (meth) acrylate, isoamyl (meth) acrylate, 3 (meth) acrylate, 3, 5-trimethylcyclohexyl ester, n-decyl (meth) acrylate, isodecyl (meth) acrylate, isobornyl (meth) acrylate, 2-propylheptyl (meth) acrylate, isotridecyl (meth) acrylate, isostearyl (meth) acrylate, octadecyl (meth) acrylate, 2-octyldecyl (meth) acrylate, dodecyl (meth) acrylate, lauryl (meth) acrylate, and heptadecyl (meth) acrylate. In some embodiments, the alkyl (meth) acrylate is a mixture of various isomers having the same number of carbon atoms as described in PCT patent application publication WO 2014/151179(Colby et al). For example, isomer mixtures of octyl (meth) acrylate may be used.

The amount of the second monomer that is a polar monomer and/or an alkyl (meth) acrylate monomer is typically in the range of 0 to 40 weight percent, 0 to 35 weight percent, 0 to 30 weight percent, 5 to 40 weight percent, or 10 to 40 weight percent, based on the total weight of the polymerizable material.

The total amount of polymerizable material is typically at least 10 wt-%, at least 12 wt-%, at least 15 wt-%, or at least 18 wt-%, based on the total weight of the photopolymerizable slurry. The amount of polymerizable material may be up to 50 wt%, up to 40 wt%, up to 30 wt%, or up to 20 wt%, based on the total weight of the photopolymerizable slurry. For example, the amount of polymerizable material can range from 10 wt% to 50 wt%, 15 wt% to 40 wt%, 15 wt% to 30 wt%, or 10 wt% to 20 wt% based on the total weight of the photopolymerizable slurry.

In general, the polymerizable material typically comprises 20 to 100 weight percent of the first monomer and 0 to 80 weight percent of the second monomer, based on the total weight of the polymerizable material. For example, the polymerizable material includes 30 to 100 wt% of the first monomer and 0 to 70 wt% of the second monomer, 30 to 90 wt% of the first monomer and 10 to 70 wt% of the second monomer, 30 to 80 wt% of the first monomer and 20 to 70 wt% of the second monomer, 30 to 70 wt% of the first monomer and 30 to 70 wt% of the second monomer, 40 to 90 wt% of the first monomer and 10 to 60 wt% of the second monomer, 40 to 80 wt% of the first monomer and 20 to 60 wt% of the second monomer, 50 to 90 wt% of the first monomer and 10 to 50 wt% of the second monomer, or 60 to 90 wt% of the first monomer and 10 to 40 wt% of the second monomer.

Photoinitiator

The photopolymerizable slurries described herein also contain one or more photoinitiators. In certain embodiments, the one or more photoinitiators may be characterized by being soluble in a solvent contained in the slurry and/or absorbing radiation in the range of 200nm to 500nm or 300nm to 470 nm. The photoinitiator should be capable of initiating or initiating a curing or hardening reaction of one or more radiation curable components present in the photopolymerizable slurry.

One or more photoinitiators of the following classes may be used: a) a two-component system in which the free radical is generated by abstraction of a hydrogen atom from a donor compound; b) one-component systems in which two radicals are generated by cleavage; and/or c) comprises iodine

A salt, a visible light sensitizer, and an electron donor compound.

Examples of photoinitiators according to type (a) generally comprise a moiety selected from benzophenone, xanthone or quinone in combination with an aliphatic amine.

Examples of photoinitiators according to type (b) typically comprise a moiety selected from benzoin ether, acetophenone, benzoyl oxime or acyl phosphine. Suitable exemplary photoinitiators are those available from Efformin Resins, Inc. (IGM Resins, Waalwijk, The Netherlands) under The trade name OMNIRAD, and include 1-hydroxycyclohexyl phenyl ketone (OMNIRAD 184), 2-dimethoxy-1, 2-diphenylethan-1-one (OMNIRAD 651), bis (2,4, 6-trimethylbenzoyl) phenyl phosphine oxide (OMNIRAD 819), 1- [4- (2-hydroxyethoxy) phenyl ] -2-hydroxy-2-methyl-1-propan-1-one (OMNIRAD 2959), 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) butanone (OMNIRAD 369), 2-methyl-1- [4- (methylthio) phenyl ] -2-morpholinopropan-1-One (OMNI) 907) 2-hydroxy-2-methyl-1-phenylpropan-1-one (OMNIRAD 1173), 2,4, 6-trimethylbenzoyldiphenylphosphine oxide (OMNIRAD TPO) and 2,4, 6-trimethylbenzoylphenylphosphinate (OMNIRAD TPO-L). Additional suitable photoinitiators include, for example and without limitation, polymerization [ 2-hydroxy-2-methyl-1- [4- (1-methylvinyl) phenyl ] propanone ] ESACURE ONE (Lamberti s.p.a., Gallarate, Italy), 2-hydroxy-2-methyl propiophenone, benzyl dimethyl ketal, 2-methyl-2-hydroxy propiophenone, benzoin methyl ether, benzoin isopropyl ether, anisoin methyl ether, aromatic sulfonyl chloride, photosensitive oximes, and combinations thereof.

Examples of photoinitiators according to type (c) generally comprise the following part of each component: suitable iodine

Salts are described in U.S. Pat. Nos. 3,729,313, 3,741,769, 3,808,006, 4,250,053 and 4,394,403 for iodine

The salt disclosure is incorporated herein by reference. Iodine

The salt may be a salt comprising, for example, Cl^-、Br^-、I^-Or C₄H₅SO₃ ^-A mono-salt of the anion of (a); or contain elements such as SbF₅OH^-Or AsF₆ ^-Metal complex salts of antimonates, arsenates, phosphates or borates. Iodine may be used if necessary

A mixture of salts. For example, suitable iodine

Salts include diphenyl iodide, all commercially available from Sigma Aldrich, st

Hexafluorophosphate and diphenyliodide

Each of the chlorides. The visible light sensitizer can be selected from ketones, coumarin dyes (e.g., coumarone), xanthene dyes, acridine dyes, thiazole dyes, thiazine dyes, oxazine dyes, azine dyes, aminoketone dyes, porphyrins, aromatic polycyclic hydrocarbons, para-substituted aminostyryl ketone compounds, aminotriarylmethanes, merocyanines, squaraine dyes, and pyridinium dyes. Preferably, the visible light sensitizer is an alpha-diketone; camphorquinone is particularly preferred and is commercially available from Sigma Aldrich (Sigma-Aldrich). The electron donor compound is typically an alkyl aromatic polyether or an alkyl, aryl amino compound in which the aryl group is substituted with one or more electron withdrawing groups. Examples of suitable electron withdrawing groups include carboxylic acid groups, carboxylate groups, ketone groups, aldehyde groups, sulfonic acid groups, sulfonate groups, and nitrile groups. The electron donor compound can be selected from polycyclic aromatic compounds such as biphenylene, naphthalene, anthracene, benzanthracene, pyrene, azulene, pentacene, decacycloalkene, and derivatives (e.g., acenaphthylene) and combinations thereof, and N-alkyl carbazole compounds (e.g., N-methyl carbazole). Preferred donor compounds include 4-dimethylaminobenzoic acid, ethyl 4-dimethylaminobenzoate, 3-dimethylaminobenzoate, 4-dimethylaminobenzaldehyde, 4-dimethylaminobenzonitrile and 1,2, 4-trimethoxybenzene. Photoinitiators according to type (c) are described in detail, for example, in commonly owned U.S. patent 6,187,833(Oxman et al).

The photoinitiator may be present in the photopolymerizable slurry described herein in any amount according to the specific limitations of the laminate manufacturing process. In some embodiments, the photoinitiator is present in an amount of 0.0051 wt% or more, 0.01 wt% or more, 0.1 wt% or more, or 0.3 wt% or more, based on the total weight of the photopolymerizable slurry; and is present in the photopolymerizable slurry in an amount of 5 wt% or less, 4 wt% or less, 3 wt% or less, 2 wt% or less, 1 wt% or less, or 0.5 wt% or less. In some cases, the photoinitiator is present in an amount of about 0.01 wt% to 5 wt%, or 0.1 wt% to 2 wt%, based on the total weight of the photopolymerizable slurry.

In addition, the photopolymerizable slurries described herein may further comprise one or more sensitizers to increase the effectiveness of one or more photoinitiators that may also be present. In some embodiments, the sensitizer comprises Isopropylthioxanthone (ITX) or 2-Chlorothioxanthone (CTX). Other sensitizers may also be used. If used in the photopolymerizable composition, the sensitizer may be present in an amount in the range of about 0.01 wt% or about 1 wt%, based on the total weight of the photopolymerizable slurry.

Inhibitors

The photopolymerizable slurries described herein optionally further comprise one or more polymerization inhibitors. Polymerization inhibitors are typically included in the photopolymerizable slurry to provide additional thermal stability to the composition. The inhibitor may extend the shelf life of the photopolymerizable slurry, help prevent undesirable side reactions, and regulate the polymerization process of one or more radiation curable components present in the slurry. The addition of one or more inhibitors to the photopolymerizable slurry may further help to improve the accuracy or detail resolution of the surface of the ceramic article. Specific examples of one or more inhibitors that may be used include: p-Methoxyphenol (MOP), hydroquinone Monomethyl Ether (MEHQ), 2, 6-di-tert-butyl-4-methyl-phenol (BHT; Ionol), phenothiazine, 2,6, 6-tetramethyl-piperidin-1-oxyl radical (TEMPO) and mixtures thereof.

In some embodiments, the polymerization inhibitor (if used) is present in an amount of about 0.001 wt% to 2 wt%, 0.001 wt% to 5 wt%, or 0.01 wt% to 1 wt%, based on the total weight of the photopolymerizable slurry. Additionally, the stabilizer (if used) is present in the photopolymerizable compositions described herein in an amount of about 0.1% to 5%, about 0.5% to 4%, or about 1% to 3% by weight based on the total weight of the photopolymerizable composition.

The photopolymerizable slurries as described herein may also contain one or more absorption modifiers (e.g., dyes, optical brighteners, pigments, etc.) to control the depth of penetration of the actinic radiation. One suitable optical brightener is Tinopal OB, a benzoxazole, 2,2' - (2, 5-thiophenediyl) bis [5- (1, 1-dimethylethyl) ], available from BASF Corporation, Florham Park, NJ, Florham Park, flor. The absorption modulator (if used) may be present in an amount of about 0.001 wt% to 5 wt%, about 0.01 wt% to 1 wt%, about 0.1 wt% to 3 wt%, or about 0.1 wt% to 1 wt%, based on the total weight of the photopolymerizable slurry.

Solvent(s)

In many embodiments, a photopolymerizable slurry according to the present disclosure further comprises at least one (e.g., organic) solvent. Suitable solvents are generally selected to be miscible with water. Additionally, these solvents are typically selected to be soluble in supercritical carbon dioxide or liquid carbon dioxide. The molecular weight of the solvent is typically at least 25 grams per mole (g/mol), at least 30g/mol, at least 40g/mol, at least 45g/mol, at least 50g/mol, at least g/mol, or at least 100 g/mol. The molecular weight may be up to 300g/mol, up to 250g/mol, up to 225g/mol, up to 200g/mol, up to 175g/mol or up to 150 g/mol. The molecular weight is typically in the range of 25g/mol to 300g/mol, 40g/mol to 300g/mol, 50g/mol to 200g/mol, or 75g/mol to 175 g/mol. It is particularly preferred that the one or more solvents have a boiling point above the temperature employed during the laminate manufacturing process to minimize solvent evaporation and associated pore formation in the gelled article. For example, at least one solvent having a boiling point of 150 ℃ or higher, 160 ℃ or higher, 170 ℃ or higher, 180 ℃ or higher, or 190 ℃ or higher may be used. In certain embodiments, the amount of the one or more solvents in the photopolymerizable slurry is 20 weight percent or more, 25 weight percent or more, 30 weight percent or more, 35 weight percent or more, 40 weight percent or more, or 45 weight percent or more, based on the total weight of the photopolymerizable slurry; and 70 wt% or less, 65 wt% or less, 60 wt% or less, 55 wt% or less, or 50 wt% or less. In other words, the photopolymerizable slurry may comprise 20 to 70 wt% solvent, or 20 to 50 wt% solvent, based on the total weight of the photopolymerizable slurry. Advantageously, in certain embodiments, the presence of a solvent may help to maintain a pore structure in the article for removing organic material from the article. After the solvent exchange (e.g., distillation) process, the solvent medium typically comprises less than 15 wt.% water, less than 10% water, less than 5% water, less than 3% water, less than 2% water, less than 1 wt.% water, or even less than 0.5 wt.% water.

Suitable solvents include, for example, but are not limited to, diethylene glycol monoethyl ether, ethanol, l-methoxy-2-propanol (i.e., methoxypropanol), isopropanol, ethylene glycol, N-dimethylacetamide, N-methylpyrrolidone, and combinations thereof. Suitable solvents are typically glycols or polyglycols, monoether glycols or monoether polyglycols, diether glycols or diether polyglycols, ether ester glycols or ether ester polyglycols, carbonates, amides or sulfoxides (e.g. dimethyl sulfoxide). The solvent typically has one or more polar groups. The solvent having no polymerizable group; that is, the (e.g., organic) solvent is free of groups that can undergo free radical polymerization. In addition, the components of the solvent medium do not have polymerizable groups that can undergo free radical polymerization.

Suitable diols or polyglycols, monoether diols or monoether polyglycols, diether diols or diether polyglycols, and ether ester diols or ether ester polyglycols are generally of formula (I).

R¹O-(R²O)_n-R¹

(I)

In the formula (I), each R¹Independently hydrogen, alkyl, aryl or acyl. Suitable alkyl groups typically have 1 to 10 carbon atoms, 1 to 6 carbon atoms, or 1 to 4 carbon atoms. Suitable aryl groups typically have from 6 to 10 carbon atoms and are typically phenyl or substituted withPhenyl substituted with an alkyl group of 1 to 4 carbon atoms. Suitable acyl groups generally have the formula- (CO) R³Wherein R is³Is an alkyl group having 1 to 10 carbon atoms, 1 to 6 carbon atoms, 1 to 4 carbon atoms, 2 carbon atoms, or 1 carbon atom. Acyl is typically an acetate group (- (CO) CH₃). In the formula (I), each R²Typically methylene or propylene. The variable n is at least 1, and may range from 1 to 10, 1 to 6,1 to 4, or 1 to 3.

The diol or polyglycol of formula (I) has two R equal to hydrogen¹A group. Examples of glycols include, but are not limited to, ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, triethylene glycol, and tripropylene glycol.

The monoether glycol or monoether propylene glycol of formula (I) has a first R equal to hydrogen¹A group, and a second R equal to alkyl or aryl¹A group. Examples of monoether glycols or monoether polyglycols include, but are not limited to, ethylene glycol monohexyl ether, ethylene glycol monophenyl ether, propylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monopropyl ether, diethylene glycol monobutyl ether, diethylene glycol monohexyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol monopropyl ether, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, triethylene glycol monobutyl ether, tripropylene glycol monomethyl ether, and tripropylene glycol monobutyl ether.

The diether diol or diether polyglycol of formula (I) has two Rs equal to alkyl or aryl¹A group. Examples of diether glycols or diether polyglycols include, but are not limited to, ethylene glycol dipropyl ether, ethylene glycol dibutyl ether, dipropylene glycol dibutyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, and pentaethylene glycol dimethyl ether.

The ether ester diol or ether ester polyglycol of formula (I) has a first R equal to alkyl or aryl¹A group, and a second R equal to acyl¹A group. Examples of ether ester diols or ether ester polyglycols include, but are not limited to, ethylene glycol butyl ether acetate, diethylene glycol butyl ether acetate, and diethylene glycol ethyl ether acetate.

Other suitable solvents are carbonates of the formula (II).

In the formula (II), R⁴Is hydrogen or an alkyl group, such as an alkyl group having 1 to 4 carbon atoms, 1 to 3 carbon atoms, or 1 carbon atom. Examples include ethylene carbonate and propylene carbonate.

Other suitable solvents are amides of formula (III).

In formula (III), the radical R⁵Is hydrogen, alkyl, or with R⁶Combined to form a composition comprising a linker linked to R⁵And is attached to R⁶A five-membered ring of the nitrogen atom of (1). Radical R⁶Is hydrogen, alkyl, or with R⁵Combined to form a composition comprising a linker linked to R⁵And is attached to R⁶A five-membered ring of the nitrogen atom of (1). Radical R⁷Is hydrogen or alkyl. Is suitable for R⁵、R⁶And R⁷The alkyl group of (a) has 1 to 6 carbon atoms, 1 to 4 carbon atoms, 1 to 3 carbon atoms, or 1 carbon atom. Examples of amide organic solvents of formula (III) include, but are not limited to, formamide, N-dimethylformamide, N-dimethylacetamide, N-diethylacetamide, N-methyl-2-pyrrolidone, and N-ethyl-2-pyrrolidone.

Additionally, in certain embodiments, the photopolymerizable slurry further comprises a dispersant to aid in the distribution of the non-oxide ceramic particles in the photopolymerizable slurry. Typically, the one or more dispersants may be present in an amount of 0.5 wt% or more, 0.55 wt% or more, 0.60 wt% or more, 0.65 wt% or more, or 0.70 wt% or more, based on the total weight of the photopolymerizable slurry; and is present in the photopolymerizable slurry in an amount of 1.0 wt.% or less, 0.95 wt.% or less, 0.90 wt.% or less, 0.85 wt.% or less, 0.80 wt.% or less, or 0.75 wt.% or less, based on the total weight of the photopolymerizable slurry. In other words, the optional dispersant may be present in an amount of 0.5 wt% to 1.0 wt%, based on the total weight of the photopolymerizable slurry. Suitable dispersants include, for example and without limitation, dispersants available from Lubrizol, Wickliffe, OH, of wilcliff, ohio under the trade name SOLPLUS or SOLSPERSE, such as SOLPLUS D510, R700, R720, D540, D545, and D570, SOLSPERSE 20000, S71000, M387, M389, S41000, and S79000, and combinations thereof.

The photopolymerizable composition materials herein can also exhibit a variety of desirable properties, be uncured, be cured, and be post-cured articles. The photopolymerizable slurry (e.g., uncured) has a viscosity profile that meets the requirements and parameters of one or more layup manufacturing devices (e.g., 3D printing systems). In certain embodiments, the photopolymerizable slurry exhibits a dynamic viscosity at 23 degrees Celsius of 500 millipascal seconds (mPa-s) or less, 400 mPa-s or less, 300 mPa-s or less, 200 mPa-s or less, 100 mPa-s or less, 50 mPa-s or less, or 25 mPa-s or less. In some cases, when uncured, the photopolymerizable slurries described herein exhibit a dynamic viscosity of 1 to 500, 1 to 100, or 1 to 50 mPa-s using a Brookfield DV-E viscometer (Brookfield Engineering Laboratories, Middleboro, MA), using a disk rotor and a cylindrical rotor, at 23 degrees Celsius and a shear rate of 21/s to 201/s. In some cases, the photopolymerizable compositions described herein exhibit a dynamic viscosity of less than about 50 mPa-s when uncured.

Slurry liquid

The preparation of photopolymerizable slurries is generally carried out under light-limiting conditions to avoid undesirable premature polymerization. Generally, the photopolymerizable slurry is prepared by rapidly mixing the components to form a preferably homogeneous slurry. Prior to use, the slurry is typically stored in a suitable device such as a receptacle, bottle, cartridge or container.

Article of manufacture

In a second aspect, the present disclosure provides an aerogel. The aerogel comprises:

a) an organic material;

b) non-oxide ceramic particles in a range from 29 to 75 weight percent based on the total weight percent of the aerogel; and

c) at least one sintering aid.

In a third aspect, the present disclosure provides a xerogel. The xerogel comprises:

a) an organic material;

b) non-oxide ceramic particles in a range of 29 to 75 weight percent based on the total weight percent of the xerogel; and

c) at least one sintering aid.

The components of the organic material, the non-oxide ceramic particles, and the sintering aid of each of the second and third aspects are as discussed in detail above. When formed using a laminate manufacturing process, aerogel or xerogel articles typically comprise multiple layers.

As mentioned above, aerogels are porous materials derived from gels in which the liquid component of the gel is replaced with a gas. The removal of the solvent is usually carried out under supercritical conditions. In contrast, xerogels are three-dimensional solids derived from green body gels in which the liquid component of the gel has been removed by evaporation at ambient conditions or at elevated temperatures. There is no capillary action for this type of drying and the linear shrinkage is typically in the range of 0% to 25%, 0% to 20%, 0% to 15%, 5% to 15%, or 0% to 10%. The density is generally maintained uniform throughout the structure.

The photopolymerizable slurry containing the non-oxide ceramic particles is solidified by curing (e.g., gelling). Preferably, the gelling process allows the formation of green gels of any shape without cracking, and allows further processing of the green gel without causing cracking. For example, preferably, the gelling process results in a green gel having a structure that does not collapse upon removal of the solvent; so-called "free standing gels". Preferably, the gel contains a minimal amount of organic material or polymeric modifier. After processing the photopolymerizable slurry to form the green gel, the gelled article is typically removed from the apparatus used to perform the layup manufacturing process. If necessary, the surface of the gelled article is cleaned, for example, by rinsing it with a solvent or soaking it in a solvent. Suitable solvents preferably include mixtures thereof or one or more of the same solvents used in the slurries described herein.

The green gel structure is compatible with and stable in a variety of solvents and conditions that may be required for supercritical extraction. Furthermore, the gel structure should be compatible with supercritical extraction fluids (e.g., supercritical carbon dioxide). In other words, the gel should be stable and strong enough to withstand drying to produce a stable aerogel and/or xerogel and to obtain a material that can be heated to burn out organics, pre-sinter, and densify without cracking. Preferably, the resulting aerogels and/or xerogels have relatively small and uniform pore sizes to facilitate their sintering to high densities at low sintering temperatures. Preferably, however, the pores are large enough to allow the organic-burnt product gas to escape without causing the aerogel or xerogel to crack. It is believed that the rapid nature of the gelling step results in a substantially uniform distribution of non-oxide ceramic particles throughout the gel, which can facilitate subsequent processing steps such as supercritical extraction, organic burnout, and sintering.

If applied, the supercritical drying step may be characterized by at least one, more or all of the following features:

a) temperature: 20 ℃ to 100 ℃, 30 ℃ to 80 ℃ or 15 ℃ to 150 ℃;

b) pressure: 5 to 200MPa, 10 to 100MPa, 1 to 20MPa or 5 to 15 MPa;

c) duration: 2 to 175 hours, 5 to 25 hours, or 1 to 5 hours; and

d) extraction or drying medium: carbon dioxide in its supercritical stage.

Combinations of features (a), (b) and (d) are sometimes preferred.

Supercritical extraction can remove all or most (e.g., organic) solvents in the printed gel article. In some embodiments, the aerogel comprises some residual solvent. The residual solvent can be up to 6 weight percent, based on the total weight of the aerogel. For example, the aerogel can comprise up to 5 wt.%, up to 4 wt.%, up to 3 wt.%, up to 2 wt.%, or up to 1 wt.% (e.g., organic) solvent. Removal of the solvent results in the formation of pores within the dried structure. Preferably, the pores are large enough to allow gases from the decomposition products of the polymeric material to escape without cracking the structure when the dried structure is further heated to burn off the organic material and form a sintered article.

The article obtained after being subjected to the supercritical drying step may be generally characterized by at least one or more of the following characteristics:

showing N with hysteresis loop₂Adsorption and/or desorption isotherms;

n of type IV showing the classification and hysteresis loop according to IUPAC₂Adsorption and desorption isotherms;

n of type IV showing a hysteresis loop of type H1 according to IUPAC classification₂Adsorption and desorption isotherms;

n of type IV with hysteresis loop of type H1, shown according to IUPAC classification, in the range of p/p0 from 0.70 to 0.99₂Adsorption and desorption isotherms;

heat treating the aerogel or xerogel article to form a porous ceramic article can be at 200 degrees celsius (° c) or more, 300 ℃ or more, 400 ℃ or more, 500 ℃ or more, 600 ℃ or more, or 700 ℃ or more (typically in an atmosphere comprising oxygen); and at a temperature of 1200 ℃ or less, 1100 ℃ or less, 1000 ℃ or less, 900 ℃ or less, or 800 ℃ or less. In other words, the heat treatment may be performed at a temperature of 200 ℃ to 1200 ℃.

In a fourth aspect, a porous ceramic article is provided. The porous ceramic article comprises:

a) non-oxide ceramic particles in a range of 90 wt% to 99 wt%, based on the total weight of the porous ceramic article; and

b) at least one sintering aid, wherein the sintering aid is selected from the group consisting of,

wherein the non-oxide ceramic particles define one or more tortuous or arcuate channels, one or more internal architectural voids, one or more undercuts, one or more perforations, or a combination thereof in the porous ceramic article, and wherein the porous ceramic article comprises at least one feature integral to the porous ceramic article, the feature having a dimension of 0.5mm length or less.

The components of the non-oxide ceramic particles and the sintering aid of the fourth aspect are as discussed in detail above. The shape of the article is not limited and may include a shaped monolithic article. In many embodiments, the article comprises a shaped monolithic article, wherein a single monolithic article provides more than one dimensional change. For example, the article may include one or more tortuous or arcuate pathways, one or more internal architectural voids, one or more undercuts, one or more perforations, or a combination thereof. Such features are generally not available in monolithic articles using conventional molding processes. "internal architectural void" means a void that is completely enclosed within the ceramic article (e.g., does not extend to any exterior surface of the ceramic article) and that has a designed shape, such as programmed into a stack manufacturing apparatus for selectively curing a photopolymerizable slurry to form the shape of the ceramic article. The internal architectural voids are in contrast to the internal pores formed during the manufacture of the ceramic articles. In selected embodiments, the article comprises a liner or gasket having high chemical resistance.

Finally, a sintering step is performed to obtain a non-oxide ceramic article having a density of 95% or greater, 96% or greater, 97% or greater, 98% or greater, 99% or greater, 99.5% or greater, or 99.9% or greater of theoretical density. Sintering of porous ceramic articles is typically carried out under the following conditions:

temperature: 1700 ℃ to 2300 ℃, 1700 ℃ to 2000 ℃, 2050 ℃ to 2300 ℃ or 1800 ℃ to 2100 ℃; or 1700 ℃ or higher, 1750 ℃ or higher, 1800 ℃ or higher, greater than 1850 ℃ or higher, or 1900 ℃ or higher; and 2300 ℃ or less, 2250 ℃ or less, 2200 ℃ or less, 2150 ℃ or less, 2100 ℃ or less, 2050 ℃ or less, or 2000 ℃ or less;

atmospheric environment: inert gases (e.g., nitrogen, argon);

pressure: ambient pressure (e.g., 1013 mbar); and

duration: until the density reaches 95% to 100% of the final density of the material.

Alternatively to ambient pressure, sintering may be carried out at elevated or reduced pressure.

In a fifth aspect, a non-oxide ceramic article is provided. The non-oxide ceramic article comprises: a non-oxide ceramic material defining one or more tortuous or arcuate pathways, one or more internal architectural voids, one or more undercuts, one or more perforations, or a combination thereof in the non-oxide ceramic article; wherein the non-oxide ceramic article exhibits a density of 95% or greater relative to a theoretical density of the non-oxide ceramic material, and wherein the non-oxide ceramic article comprises at least one feature integral to the non-oxide ceramic article, the feature having a dimension of 0.5mm in length or less.

The composition of the non-oxide ceramic particles of the fifth aspect is as discussed in detail above. Preferably, the non-oxide ceramic particles are selected from the group consisting of silicon carbide, silicon nitride, boron carbide, titanium diboride, zirconium diboride, boron nitride, and combinations thereof.

For volume a scaled to 100, the relationship of the various volumes of material formed according to at least some embodiments is as follows:

volume a (gelled product) is 100.

Volume B (post-cured gelled article) is 90 to 100.

Volume C (xerogel product) 75 to 90

Volume D (aerogel product) 85 to 95

Volume E (white blank) 40 to 75

Volume F (fully sintered ceramic article) < 45.

Thus, the gelled article has a volume a, the sintered ceramic article has a volume F, and wherein the volume F of the sintered ceramic article is less than 45% of the volume a of the gelled article.

Computer modeling, such as Computer Aided Design (CAD) data, can be used to generate data representing an article (e.g., a gelled article). Image data representing the article design may be exported into the layup manufacturing facility in STL format or any other suitable computer-processable format. Scanning methods may also be employed to scan three-dimensional objects to create data representative of an article. One exemplary technique for acquiring data is digital scanning. The article may be scanned using any other suitable scanning technique, including radiography, laser scanning, Computed Tomography (CT), Magnetic Resonance Imaging (MRI), and ultrasound imaging. Other possible scanning methods are described in U.S. patent application publication 2007/0031791(Cinader, jr. et al). An initial digital data set, which may include both raw data from a scanning operation and data representative of an article derived from the raw data, may be processed to segment the article design from any surrounding structure (e.g., a support for the article).

Typically, the machine-readable medium is provided as part of a computing device. The computing device may have one or more processors, volatile memory (RAM), means for reading the machine-readable medium, and input/output devices such as a display, a keyboard, and a pointing device. Additionally, the computing device may also include other software, firmware, or combinations thereof, such as an operating system and other application software. The computing device may be, for example, a workstation, a laptop, a Personal Digital Assistant (PDA), a server, a mainframe, or any other general purpose or application specific computing device. The computing device may read the executable software instructions from a computer-readable medium, such as a hard disk, CD-ROM, or computer memory, or may receive the instructions from another source logically connected to the computer, such as another networked computer. Referring to fig. 10, computing device 1000 typically includes an internal processor 1080, a display 1100 (e.g., a monitor), and one or more input devices such as a keyboard 1140 and a mouse 1120. In FIG. 10, gelled article 1130 is shown on display 1100.

Referring to fig. 6, in certain embodiments, the present disclosure provides a system 600. The system 600 includes a display 620 that displays a 3D model 610 of an article (e.g., a gelled article 1130 as shown on the display 1100 of fig. 10); and one or more processors 630 that, in response to the 3D model 610 selected by the user, cause the 3D printer/layered manufacturing apparatus 650 to generate a physical object of the article 660. Generally, an input device 640 (e.g., a keyboard and/or mouse) is used with the display 620 and the at least one processor 630, particularly for user selection of the 3D model 610. Article 660 comprises a gelled article obtained by selectively curing a photopolymerizable slurry. The photopolymerizable slurry comprises non-oxide ceramic particles; at least one radiation curable monomer; a solvent; a photoinitiator; an inhibitor; and at least one sintering aid. The components of the non-oxide ceramic particles, radiation curable monomer, photoinitiator, inhibitor, and sintering aid are as discussed in detail above.

Referring to fig. 7, a processor 720 (or more than one processor) communicates with each of a machine-readable medium 710 (e.g., a non-transitory medium), a 3D printer/layup manufacturing apparatus 740, and optionally a display 730, for viewing by a user. The 3D printer/layup manufacturing apparatus 740 is configured to prepare one or more articles 750 based on instructions from the processor 720, which provides data representing a 3D model of the article 750 (e.g., gelled article 1130 as shown on display 1100 of fig. 10) from the machine-readable medium 710.

Referring to fig. 8, for example and without limitation, a layup manufacturing method includes retrieving 810 data representing a 3D model of an article of manufacture according to at least one embodiment of the present disclosure from a (e.g., non-transitory) machine readable medium. The method further includes executing 820, by the one or more processors, an overlay manufacturing application interfacing with the manufacturing device using the data; and generating 830 a physical object of the article by the manufacturing apparatus. The layup manufacturing apparatus can selectively cure the photopolymerizable slurry to form a gelled article. The photopolymerizable slurry comprises non-oxide ceramic particles; at least one radiation curable monomer; a solvent; a photoinitiator; an inhibitor; and at least one sintering aid. The components of the non-oxide ceramic particles, radiation curable monomer, photoinitiator, inhibitor, and sintering aid are as discussed in detail above. One or more of various optional post-treatment steps 840 can be performed. Typically, the gelled article is dried, heat treated and sintered to form a ceramic article.

Additionally, referring to fig. 9, a method of making an article of manufacture includes receiving 910, by a manufacturing device having one or more processors, a digital object containing data specifying a plurality of layers of the article of manufacture; and generating 920 an article based on the digital object through a lamination manufacturing process using the manufacturing apparatus. Likewise, the article may undergo one or more steps of post-processing 930.

Selected embodiments of the disclosure

Embodiment 1 is a method of making a non-oxide ceramic component. The method comprises the following steps: a) obtaining a photopolymerizable slurry; b) selectively curing the photopolymerizable slurry to obtain a gelled article; c) drying the gelled article to form an aerogel or xerogel article; d) heat treating the aerogel or xerogel article to form a porous ceramic article; and e) sintering the porous ceramic article to obtain a sintered ceramic article. The photopolymerizable slurry comprises non-oxide ceramic particles; at least one radiation curable monomer; a solvent; a photoinitiator; an inhibitor; and at least one sintering aid.

Embodiment 2 is the method of embodiment 1, wherein the drying is performed by applying a supercritical fluid drying step.

Embodiment 3 is the method of embodiment 1 or embodiment 2, wherein the photopolymerizable slurry comprises less than 30 wt% of the non-oxide ceramic particles based on the total weight of the photopolymerizable slurry.

Embodiment 4 is the method of any one of embodiments 1 to 3, wherein the photopolymerizable slurry comprises between 20 wt% and up to 30 wt% but excludes 30 wt% non-oxide ceramic particles based on the total weight of the photopolymerizable slurry.

Embodiment 5 is the method of any of embodiments 1-4, wherein the gelled article has a volume a, the sintered ceramic article has a volume F, and wherein the volume F of the sintered ceramic article is less than 45% of the volume a of the gelled article.

Embodiment 6 is the method of any one of embodiments 1 to 5, wherein the non-oxide ceramic particles are selected from the group consisting of silicon carbide, silicon nitride, boron carbide, titanium diboride, zirconium diboride, boron nitride, titanium carbide, zirconium carbide, aluminum nitride, calcium hexaboride, MAX phases, and combinations thereof.

Embodiment 7 is the method of any one of embodiments 1 to 6, wherein the non-oxide ceramic particles have an average particle size of 250 nanometers to 10 micrometers, 1 micrometer to 10 micrometers, or 500 nanometers to 1.5 micrometers.

Embodiment 8 is the method of any one of embodiments 1 to 7, wherein the photoinitiator comprises iodine

A salt, a visible light sensitizer, and an electron donor compound.

Embodiment 9 is the method of embodiment 8, wherein the iodine

The salt comprises diphenyl iodide

Hexafluorophosphate and/or diphenyl iodide

A chloride, the visible light sensitizer comprises camphorquinone, and the electron donor compound comprises ethyl 4-dimethylaminobenzoate.

Embodiment 10 is the method of any of embodiments 1-9, wherein the sintered ceramic article comprises at least one feature integral to the sintered ceramic article, the feature having a dimension of 0.5 millimeter in length or less.

Embodiment 11 is the method of any one of embodiments 1 to 10, wherein at least a portion of the non-oxide ceramic particles in the photopolymerizable slurry have a surface modifier attached to the surface of the non-oxide ceramic particles.

Embodiment 12 is the method of any one of embodiments 1 to 11, wherein the photopolymerizable slurry comprises between 20 wt.% and 70 wt.% of the solvent based on the total weight of the photopolymerizable slurry.

Embodiment 13 is the method of any one of embodiments 1 to 12, wherein the solvent is selected from the group consisting of diethylene glycol monoethyl ether, ethanol, l-methoxy-2-propanol, N-methylpyrrolidone, and combinations thereof.

Embodiment 14 is the method of any one of embodiments 1 to 13, wherein the photopolymerizable slurry further comprises a dispersant.

Embodiment 15 is the method of any one of embodiments 1 to 14, wherein the at least one sintering aid comprises alumina, yttria, zirconia, silica, titania, magnesia, calcia, strontia, baria, lithia, sodium oxide, potassia, carbon, boron carbide, aluminum nitride, or a combination thereof.

Embodiment 16 is the method of any one of embodiments 1 to 15, wherein the photopolymerizable slurry further comprises an optical brightener.

Embodiment 17 is the method of any one of embodiments 1 to 16, wherein the at least one radiation curable monomer comprises an acrylate.

Embodiment 18 is the method of any one of embodiments 1 to 17, wherein the photopolymerizable slurry exhibits a viscosity of less than 500 mPa-s at 23 degrees celsius.

Embodiment 19 is the method of any one of embodiments 1 to 18, wherein the selectively curing the photopolymerizable slurry comprises curing a portion of the photopolymerizable slurry having a thickness between 3 and 50 microns.

Embodiment 20 is the method of embodiment 19, wherein the selectively curing the photopolymerizable slurry is repeated at least twice to form the gelled article.

Embodiment 21 is the method of any one of embodiments 1 to 20, wherein the heat treating is performed at a temperature of 200 to 1200 degrees celsius.

Embodiment 22 is the method of any one of embodiments 1 to 21, wherein the sintering the porous ceramic article is performed at ambient pressure.

Embodiment 23 is the method of any one of embodiments 1 to 22, wherein the sintering the porous ceramic article is performed at a temperature of 1700 degrees celsius to 2300 degrees celsius.

Embodiment 24 is the method of any one of embodiments 1 to 23, wherein the sintered ceramic article exhibits a density of 95% or greater relative to a theoretical density of the non-oxide ceramic particles.

Embodiment 25 is the method of any one of embodiments 1 to 24, wherein the selectively curing comprises printing with stereolithography.

Embodiment 26 is an aerogel. The aerogel comprises: a) an organic material; b) non-oxide ceramic particles in a range from 29 to 75 weight percent based on the total weight percent of the aerogel; and c) at least one sintering aid.

Embodiment 27 is the aerogel of embodiment 26, wherein the non-oxide ceramic particles are selected from the group consisting of silicon carbide, silicon nitride, boron carbide, titanium diboride, zirconium diboride, boron nitride, titanium carbide, zirconium carbide, aluminum nitride, calcium hexaboride, MAX phases, and combinations thereof.

Embodiment 28 is the aerogel of embodiment 26 or embodiment 27, wherein the non-oxide ceramic particles have an average particle size of 250 nanometers to 10 micrometers.

Embodiment 29 is the aerogel of any one of embodiments 26 to 28, wherein the non-oxide ceramic particles have an average particle size of 1 to 10 microns.

Embodiment 30 is the aerogel of any one of embodiments 26 to 29, wherein the non-oxide ceramic particles have an average particle size of 500 nanometers to 1.5 micrometers.

Embodiment 31 is the aerogel of any of embodiments 26-30, wherein the sintered ceramic article comprises at least one feature integral to the aerogel, the feature having a dimension of 0.5 millimeter in length or less.

Embodiment 32 is the aerogel of any of embodiments 26-31, wherein at least a portion of the non-oxide ceramic particles comprise a surface modifier attached to the surface of the non-oxide ceramic particles.

Embodiment 33 is the aerogel of any of embodiments 26 to 32, wherein the at least one sintering aid comprises alumina, yttria, zirconia, titania, magnesia, beryllia, calcia, strontia, baria, lithia, sodium oxide, potassium oxide, rubidium oxide, cesium oxide, carbon, boron carbide, aluminum, or a combination thereof.

Embodiment 34 is a xerogel. The xerogel comprises: a) an organic material; b) non-oxide ceramic particles in a range from 29 to 75 weight percent based on the total weight percent of the xerogel; and c) at least one sintering aid.

Embodiment 35 is the xerogel of embodiment 34 wherein the non-oxide ceramic particles are selected from the group consisting of silicon carbide, silicon nitride, boron carbide, titanium diboride, zirconium diboride, boron nitride, and combinations thereof.

Embodiment 36 is the xerogel of embodiment 34 or embodiment 35 wherein the non-oxide ceramic particles have an average particle size of 250 nanometers to 10 microns.

Embodiment 37 is the xerogel of any one of embodiments 34 to 36 wherein the non-oxide ceramic particles have an average particle size of 1 to 10 microns.

Embodiment 38 is the xerogel of any one of embodiments 34 to 37 wherein the non-oxide ceramic particles have an average particle size of 500 nanometers to 1.5 microns.

Embodiment 39 is a xerogel according to any one of embodiments 34 to 38 wherein the sintered ceramic article comprises at least one feature integral to the xerogel, the feature having a dimension of 0.5mm in length or less.

Embodiment 40 is the xerogel of any one of embodiments 34 to 39 wherein at least a portion of the non-oxide ceramic particles comprise a surface modifier attached to the surface of the non-oxide ceramic particles.

Embodiment 41 is the xerogel of any one of embodiments 34 to 40 wherein the at least one sintering aid comprises alumina, yttria, zirconia, silica, titania, magnesia, calcia, strontium oxide, barium oxide, lithium oxide, sodium oxide, potassium oxide, carbon, boron carbide, aluminum nitride, or combinations thereof.

Embodiment 42 is a porous ceramic article. The porous ceramic article comprises: a) non-oxide ceramic particles in a range of 90 wt% to 99 wt%, based on the total weight of the porous ceramic article; and b) at least one sintering aid. The non-oxide ceramic particles define one or more tortuous or arcuate channels, one or more internal architectural voids, one or more undercuts, one or more perforations, or a combination thereof in the porous ceramic article. The porous ceramic article includes at least one feature integral to the porous ceramic article, the feature having a dimension of 0.5mm in length or less.

Embodiment 43 is the porous ceramic article of embodiment 42, wherein the non-oxide ceramic particles are selected from the group consisting of silicon carbide, silicon nitride, boron carbide, titanium diboride, zirconium diboride, boron nitride, titanium carbide, zirconium carbide, aluminum nitride, calcium hexaboride, MAX phases, and combinations thereof.

Embodiment 44 is the porous ceramic article of embodiment 42 or embodiment 43, wherein the non-oxide ceramic particles have an average particle size of 250 nanometers to 10 micrometers.

Embodiment 45 is the porous ceramic article of any one of embodiments 42 to 44, wherein the non-oxide ceramic particles have an average particle size of 1 micron to 10 microns.

Embodiment 46 is the porous ceramic article of any one of embodiments 42 to 44, wherein the non-oxide ceramic particles have an average particle size of 500 nanometers to 1.5 micrometers.

Embodiment 47 is the porous ceramic article of any of embodiments 42-46, wherein the sintered ceramic article comprises at least one feature integral to the porous ceramic article, the feature having a dimension of 0.5 millimeter in length or less.

Embodiment 48 is the porous ceramic article of any one of embodiments 42 to 47, wherein at least a portion of the non-oxide ceramic particles comprise a surface modifier attached to a surface of the non-oxide ceramic particles.

Embodiment 49 is the porous ceramic article of any one of embodiments 42 to 48, wherein the at least one sintering aid comprises alumina, yttria, zirconia, silica, titania, magnesia, calcia, strontium oxide, barium oxide, lithium oxide, sodium oxide, potassium oxide, carbon, boron carbide, aluminum nitride, or a combination thereof.

Embodiment 50 is a non-oxide ceramic article. The non-oxide ceramic material defines one or more tortuous or arcuate pathways, one or more internal architectural voids, one or more undercuts, one or more perforations, or a combination thereof in the non-oxide ceramic article. The non-oxide ceramic article exhibits a density of 95% or greater relative to a theoretical density of the non-oxide ceramic material. The non-oxide ceramic article includes at least one feature integral to the non-oxide ceramic article, the feature having a dimension of 0.5mm in length or less.

Embodiment 51 is the non-oxide ceramic article of embodiment 50, wherein the non-oxide ceramic particles are selected from the group consisting of silicon carbide, silicon nitride, boron carbide, titanium diboride, zirconium diboride, boron nitride, and combinations thereof.

Embodiment 52 is a method. The method comprises the following steps: a) retrieving data representing a 3D model of an article from a non-transitory machine-readable medium; b) executing, by one or more processors, a 3D printing application interfacing with a manufacturing device using the data; and c) generating a physical object of the article by the manufacturing apparatus, the article comprising a gelled article obtained by selectively curing a photopolymerizable slurry. The photopolymerizable slurry comprises non-oxide ceramic particles; at least one radiation curable monomer; a solvent; a photoinitiator; an inhibitor; and at least one sintering aid.

Embodiment 53 is a method. The method comprises the following steps: a) receiving, by a manufacturing device having one or more processors, a digital object containing data specifying a plurality of layers of an article; and b) based on the digital object, generating the article by a laminate manufacturing process using the manufacturing apparatus, the article comprising a gelled article obtained by selectively curing a photopolymerizable slurry. The photopolymerizable slurry comprises non-oxide ceramic particles; at least one radiation curable monomer; a solvent; a photoinitiator; an inhibitor; and at least one sintering aid.

Embodiment 54 is an article produced using the method of embodiment 53.

Embodiment 55 is a system. The system includes a display that displays a 3D model of an article; and one or more processors responsive to the 3D model selected by the user to cause the 3D printer to produce a physical object of an article comprising a gelled article obtained by selectively curing a photopolymerizable slurry. The photopolymerizable slurry comprises non-oxide ceramic particles; at least one radiation curable monomer; a solvent; a photoinitiator; an inhibitor; and at least one sintering aid.

Embodiment 56 is a non-transitory machine readable medium. The non-transitory machine readable medium contains data representing a three-dimensional model of an article that, when accessed by one or more processors interfaced with a 3D printer, causes the 3D printer to produce an article comprising a reaction product of a photopolymerizable slurry. The photopolymerizable slurry comprises non-oxide ceramic particles; at least one radiation curable monomer; a solvent; a photoinitiator; an inhibitor; and at least one sintering aid.

Examples

Objects and advantages of this disclosure are further illustrated by the following examples, but the particular materials and amounts thereof recited in these examples, as well as other conditions and details, should not be construed to unduly limit this disclosure.

Unless otherwise indicated, all parts and percentages are by weight, all water is deionized water, and all molecular weights are weight average molecular weights. Furthermore, all experiments were carried out under ambient conditions (23 ℃; 1013 mbar) unless otherwise indicated.

Table 1: material。

Method

1. Printing

To print an object from a ceramic slurry, the following procedure was used. The build tray is assembled with a fluoropolymer release film. Approximately 50mL of slurry was loaded into the build tray at room temperature. Care was taken to prevent light exposure by performing the procedure in a UV filter chamber (yellow light) or in low light conditions when UV filtering is not available. The build platform was sanded and cleaned with IPA as needed. Sometimes the nonwoven sheet is attached to provide improved adhesion to the build platform. For some constructions, the acrylate-based layer is first cured onto the build platform before the slurry is initially cured. The stl file is loaded into the software and the support structures are applied as needed. The settings for printing in the Asiga (Sydney, Australia) Picoplus 27 stereolithography printer are listed in table 2.

Table 2: standard settings for building Using an Asiga Picoplus 273D Printer。

Immediately after the build, the sample was removed from the build platform and briefly rinsed with clean carbitol solvent. The sample was then placed in a sealed container until the next step.

2. Supercritical extraction

The supercritical extraction step was performed using a 10L laboratory supercritical fluid extractor apparatus designed and obtained from Thar Process, inc. Based on SiO₂The gel of (a) was mounted in a stainless steel frame. Sufficient ethanol was added to the 10L extractor reservoir to cover the gel (about 3500ml-6500 ml). Stainless steel racks containing wet silica-based gel were loaded into a 10L extractor such that the wet gel was completely submerged in liquid ethanol within a jacketed extractor vessel, which was heated and maintained at 60 ℃. After sealing the extractor vessel cover in place, liquid carbon dioxide is pumped by a chilled piston pump (condensation point: -8.0 ℃) and CO is passed through a heat exchanger₂Heat to 60 ℃, and the carbon dioxide enters a 10L extractor reservoir until an internal pressure of 13.3MPa is reached. Under these conditions, carbon dioxide is supercritical. When the extractor operating conditions of 13.3MPa and 60 ℃ were met, a needle valve regulated the pressure in the extractor vessel by opening and closing and the extractor effluent was passed through a 316L stainless steel porous frit (model 1100S-5.480DIA-062-10-A from Mott, Inc., New Neigo, Conn.)New Britain, CT, USA)), then passed through a heat exchanger to cool the effluent to 30 ℃, and finally into a 5L cyclone vessel maintained at room temperature and a pressure of less than 5.5MPa, with the extracted ethanol and gas phase CO₂Separated and collected during the extraction cycle for recycle and reuse. From the time operating conditions are achieved, supercritical carbon dioxide (scCO)₂) Pumped through a 10L extractor reservoir for 8 hours continuously. After 8 hours of extraction cycle, the extractor vessel was slowly vented from 13.3MPa to atmospheric pressure into the cyclone over 16 hours at 60 ℃, after which the lid was opened and the stainless steel frame including the dry aerogel was removed. The dry aerogel was removed from its stainless steel frame and placed in a labeled bag.

3. Binder burn-out

Binder burn-up was accomplished in an air CM tube furnace (CM Furnaces, inc., Bloomfield, NJ) using the following burn-up profile:

in air with or without flow, to ventilate the smoke

15 h heating to 210 ℃ and holding for 30 min

28 h heating to 250 ℃ and holding for 30 min

32 h heating to 400 ℃ for 30 min

7 h heating to 600 ℃ and holding for 1 h

6 h warming to RT

4. Sintering

Sintering was done in an Astro nitrogen inert furnace (Thermal Technology, LLC, Santa Rosa, CA)) by ramping up to 305mV at 75 mV/hr (as measured by a pyrometer), which corresponds to 1770 ℃ from one perspective, as measured by a separate hand-held pyrometer. The temperature was maintained at 1770 ℃ for 3 hours and then raised to room temperature at the cooling rate of the apparatus. Some parts were sintered in a loose powder bed consisting of 45 wt% Si₃N₄45% by weight of BN, 5% by weight of Al₂O₃And 5% by weight of Y₂O₃Compositions, which were previously mixed together by rolling overnight in a jar.

5. Depth of cure analysis

The depth of cure of the slurry was analyzed using a photomask with a 4mm circle and timing the light exposure on an Asiga Pico 23D printer (Asiga USA, Anaheim Hills, CA). The depth of cure of the various compositions as a function of time is shown in table 3 below.

Table 3: depth of cure in microns as a function of seconds of cure time。

Preparation of (meth) acrylate mixtures

Preparation of S1 methacrylate

The methacrylate monomer mixture was prepared by mixing 83 wt% BPA4EO-DMA, 10 wt% HPMA, 4.67 wt% CAPA 400, 1.6 wt% OMNIRAD 819, 0.08 wt% Solvaperm-Rot PFS, and 0.04 wt% Macrolex Violett B dye with stirring until a homogeneous mixture was obtained.

531 preparation of acrylic esters

The acrylate monomer mixture was prepared by mixing 51 wt% SR399, 28.8 wt% SR351, and 20.2 wt% SR506A with stirring until a clear, homogeneous mixture was obtained.

_{3 4}SiN powder mixture

By mixing 90g of Si of SILZOT type or SN-E10 type₃N₄Preparation of Si powder by mixing the powder with 5g of aluminium oxide powder and 5g of yttrium oxide powder₃N₄A powder mixture. In some cases, the mixture is dispersed in BIn alcohol, ball milled overnight, dried in a solvent grade oven, then ground and sieved with a 150 micron mesh size. In other cases, the mixture was added directly to the liquid component of the slurry and ball milled overnight as a slurry.

Table 4: resin composition

Example #	CE1	CE2	E3	E4	CE5	E6	E7	E8
									Si3N4Powder mixture (g)	30	30	30	30	20	20	20	30
S1 methacrylate (g)	45	52.5	-	-	-	-	-	-
									531 acrylic ester (g)	-	-	25	25	40	25	25	25
Carbitol (g)	25	17.5	45	45	40	55	55	45
									Solplus dispersant (g)	1	1	1	1	1	1	1	1
OMNIRAD 819(g)	-	-	0.5	0.5	1	0.5	0.5	-
									BHT(g)	-	-	0.05	0.05	0.2	0.1	0.1	0.1
Acrylic ester naphthalimide (g)	-	-	-	0.025	-	-	-	-
									CPQ(g)	-	-	-	-	-	-	-	0.15
EDMAB(g)	-	-	-	-	-	-	-	0.55
									DPIHFP(g)	-	-	-	-	-	-	-	0.15

Comparative example 1(CE1)

In a polymer jar, the following table 4 will be usedThe resin component (a) was mixed with the grinding media and rolled overnight to completely disperse the powder. Using a cylinder tray with a fluoropolymer release film and printing parameters as described above, the slurry was printed on a nonwoven spun-bonded nylon tape adhered to a build platform in an Asiga Picoplus 3D printer (Asiga USA, Anaheim Hills, CA) at 10 seconds exposure per 25 micron layer₂The solvent is removed by supercritical fluid extraction. After SFE, the layers of the printed component show some separation, as shown in fig. 4A. The burn-out and sintering is accomplished using the above-described signature. Additional cracks formed during burn-out and the part fragmented after sintering, as shown in fig. 4B.

Comparative example 2(CE2)

In a polymer jar, the resin composition according to table 4 above was mixed with grinding media and rolled overnight to completely disperse the powder. The slurry was printed onto a methacrylate layer cured onto a build platform in Asiga Picoplus using a cylinder tray with fluoropolymer release film and printing parameters as described above at 10 seconds exposure per 10 micron layer. Solvent was removed using supercritical fluid extraction, after which some cracking between layers was observed. The burn-out and sintering is accomplished using the above-described signature. Cracks form during burn-out and the part fragments after sintering.

Example 3(E3)

In a polymer jar, the resin composition according to table 4 above was mixed with grinding media and rolled overnight to completely disperse the powder. The slurry was printed onto a nonwoven spun-bonded nylon tape affixed to a build platform in Asiga Picoplus using a cylinder tray with fluoropolymer release film and printing parameters as described above at 3 second exposure per 10 micron layer as shown in fig. 11A. The solvent is removed using supercritical fluid extraction. The burn-out and sintering is accomplished using the above-described signature. The sintered part is complete with a single broken piece as shown in fig. 11B.

Example 4(E4)

In a polymer jar, theThe resin composition according to table 4 above was mixed with grinding media and rolled overnight to allow complete dispersion of the powder. The slurry was printed onto a nonwoven spun-bonded nylon tape affixed to a build platform in Asiga Picoplus using a cylinder tray with fluoropolymer release film and printing parameters as described above at 3 seconds exposure per 10 micron layer. The solvent is removed using supercritical fluid extraction. The burn-out and sintering is accomplished using the above-described signature. The sintered part is complete. The Archimedes density was measured to be 3.230g/cm³。

Comparative example 5(CE5)

In a polymer jar, the resin composition according to table 4 above was mixed with grinding media and rolled overnight to completely disperse the powder. The slurry was printed onto a nonwoven spun-bonded nylon tape affixed to a build platform in Asiga Picoplus using a cylinder tray with fluoropolymer release film and printing parameters as described above at 1 second exposure per 10 micron layer. The printed components are shown in fig. 12A. The solvent was removed using supercritical fluid extraction, after which a large number of cracks were observed, as shown in fig. 12B. The component does not proceed with subsequent post-processing.

Example 6(E6)

In a polymer jar, the resin composition according to table 4 above was mixed with grinding media and rolled overnight to completely disperse the powder. The slurry was printed onto a nonwoven spun-bonded nylon tape affixed to a build platform in an Asiga Picoplus 3D printer at 1 second exposure per 10 micron layer using a cylinder tray with fluoropolymer release film and printing parameters as described above. The printed components are shown in fig. 13A. Solvent was successfully removed using supercritical fluid extraction, as shown in fig. 13B. Burnout and sintering were also successfully accomplished using the above-described profile, resulting in a solid final part, as shown in fig. 13C. The Archimedes density was measured to be 3.232g/cm³。

Example 7(E7)

In a polymer jar, the resin composition according to table 4 above was mixed with grinding media and rolled overnight to completely disperse the powder. Using a barrier film having a fluoropolymerAnd printing parameters as described above, the slurry was printed onto a non-woven spun-bonded nylon belt adhered to a build platform in an Asiga Picoplus 3D printer at 2 second exposure per 10 micron layer. Solvent was successfully removed using supercritical fluid extraction. Burnout and sintering were also successfully accomplished using the above-described profile to yield a solid final part. The Archimedes density was measured to be 3.221g/cm³。

Example 8(E8)

In a polymer jar, the resin composition according to table 4 above was mixed with grinding media and rolled overnight to completely disperse the powder. The slurry was printed using a cylinder tray with fluoropolymer release film and printing parameters as described above at 10 seconds exposure per 10 micron layer onto a non-woven spun-bonded nylon tape affixed to a build platform in an Asiga Picoplus 3D printer modified to use 460nm LEDs. Solvent was successfully removed using supercritical fluid extraction. Burnout and sintering were also successfully accomplished using the above-described profile to yield a solid final part.

All patents and patent applications mentioned above are hereby expressly incorporated by reference. The above-described embodiments are all illustrations of the present invention, and other configurations are also possible. Accordingly, the present invention should not be considered limited to the embodiments described in detail above and illustrated in the drawings, but should be defined only by the proper scope of the appended claims and equivalents thereof.

Claims (22)

1. A method of making a non-oxide ceramic component, the method comprising:

a) obtaining a photopolymerizable slurry comprising a plurality of non-oxide ceramic particles; at least one radiation curable monomer; a solvent; a photoinitiator; an inhibitor; and at least one sintering aid;

b) selectively curing the photopolymerizable slurry to obtain a gelled article;

c) drying the gelled article to form an aerogel or xerogel article;

d) heat treating the aerogel or xerogel article to form a porous ceramic article; and

e) sintering the porous ceramic article to obtain a sintered ceramic article.

2. The method of claim 1, wherein drying is performed by applying a supercritical fluid drying step.

3. The method of claim 1 or claim 2, wherein the photopolymerizable slurry comprises less than 30 wt% of the non-oxide ceramic particles based on the total weight of the photopolymerizable slurry.

4. The method of any one of claims 1 to 3, wherein the photopolymerizable slurry comprises between 20 wt% and up to 30 wt% but excludes 30 wt% non-oxide ceramic particles, based on the total weight of the photopolymerizable slurry.

5. The method of any one of claims 1 to 4, wherein the gelled article has a volume A, the sintered ceramic article has a volume F, and wherein the volume F of the sintered ceramic article is less than 45% of the volume A of the gelled article.

6. The method of any one of claims 1 to 5, wherein the non-oxide ceramic particles are selected from the group consisting of silicon carbide, silicon nitride, boron carbide, titanium diboride, zirconium diboride, boron nitride, titanium carbide, zirconium carbide, aluminum nitride, calcium hexaboride, MAX phases, and combinations thereof.

7. The method of any one of claims 1 to 6, wherein the non-oxide ceramic particles have an average particle size of 250 nanometers to 1 micron, 500 nanometers to 1.5 microns, or 1 micron to 10 microns.

8. The method of any one of claims 1 to 7, wherein the photoinitiator comprises iodine

A salt, a visible light sensitizer, and an electron donor compound.

9. The method of any one of claims 1 to 8, wherein the photopolymerizable slurry further comprises a dispersant.

10. The method of any one of claims 1 to 9, wherein the at least one sintering aid comprises alumina, yttria, zirconia, silica, titania, magnesia, calcia, strontia, baria, lithia, sodium oxide, potassium oxide, carbon, boron carbide, aluminum nitride, or combinations thereof.

11. The method of any one of claims 1 to 10, wherein the selectively curing the photopolymerizable slurry comprises curing a portion of the photopolymerizable slurry having a thickness between 3 and 50 microns.

12. The method of claim 11, wherein said selectively curing said photopolymerizable slurry is repeated at least twice to form said gelled article.

13. The method of any one of claims 1 to 12, wherein the sintered ceramic article exhibits a density of 95% or greater relative to a theoretical density of the non-oxide ceramic particles.

14. The method of any one of claims 1 to 13, further comprising milling the plurality of non-oxide ceramic particles into the solvent.

15. An aerogel, comprising:

a) an organic material;

b) non-oxide ceramic particles in a range from 29 to 75 weight percent based on the total weight percent of the aerogel; and

c) at least one sintering aid.

16. A xerogel comprising:

a) an organic material;

b) non-oxide ceramic particles in a range from 29 to 75 weight percent based on the total weight percent of the xerogel; and

c) at least one sintering aid.

17. A porous ceramic article, comprising:

a) non-oxide ceramic particles in a range of 90 wt% to 99 wt%, based on the total weight of the porous ceramic article; and

b) at least one sintering aid, wherein the sintering aid is selected from the group consisting of,

wherein the non-oxide ceramic particles define one or more tortuous or arcuate channels, one or more internal architectural voids, one or more undercuts, one or more perforations, or a combination thereof in the porous ceramic article, and wherein the porous ceramic article comprises at least one feature integral to the porous ceramic article, the feature having a dimension of 0.5mm length or less.

18. A non-oxide ceramic article, comprising:

a non-oxide ceramic material defining one or more tortuous or arcuate channels, one or more internal architectural voids, one or more undercuts, one or more perforations, or a combination thereof in the non-oxide ceramic article; wherein the non-oxide ceramic article exhibits a density of 95% or greater relative to a theoretical density of the non-oxide ceramic material, and wherein the non-oxide ceramic article comprises at least one feature integral to the non-oxide ceramic article, the feature having a dimension of 0.5mm length or less.

19. A method, the method comprising:

a) retrieving data representing a 3D model of an article from a non-transitory machine-readable medium;

b) executing, by one or more processors, a 3D printing application interfacing with a manufacturing device using the data; and

c) generating a physical object of the article by the manufacturing apparatus, the article comprising a gelled article obtained by selectively curing a photopolymerizable slurry comprising:

1) less than 30 weight percent non-oxide ceramic particles based on the total weight of the photopolymerizable slurry;

2) at least one radiation curable monomer;

3) a solvent;

4) a photoinitiator;

5) an inhibitor; and

6) at least one sintering aid.

20. A method, the method comprising:

a) receiving, by a manufacturing device having one or more processors, a digital object containing data specifying a plurality of layers of an article; and

b) generating, with the manufacturing apparatus, the article by a layup manufacturing process based on the digital object, the article comprising a gelled article obtained by selectively curing a photopolymerizable slurry comprising:

1) a plurality of non-oxide ceramic particles;

2) at least one radiation curable monomer;

3) a solvent;

4) a photoinitiator;

5) an inhibitor; and

6) at least one sintering aid.

21. A system, the system comprising:

a) a display that displays a 3D model of an article; and

b) one or more processors responsive to the 3D model selected by a user to cause a 3D printer to produce a physical object of an article of manufacture, the article of manufacture comprising a gelled article obtained by selectively curing a photopolymerizable syrup comprising:

1) a plurality of non-oxide ceramic particles;

2) at least one radiation curable monomer;

3) a solvent;

4) a photoinitiator;

5) an inhibitor; and

6) at least one sintering aid.

22. A non-transitory machine readable medium comprising data representing a three-dimensional model of an article, which when accessed by one or more processors interfacing with a 3D printer causes the 3D printer to produce an article comprising a reaction product of a photopolymerizable syrup comprising: a plurality of non-oxide ceramic particles; at least one radiation curable monomer; a solvent; a photoinitiator; an inhibitor; and at least one sintering aid.

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